From my personal experience as someone who really wanted to start tanking this season.
There is a reason why I stopped learning it and returned to being a DPS.
It’s just so much harder then being a DPS.
And I mean it’s not even comparable, yes playing the mechanics of a given fight while doing you DPS rota is also something that needs some learning but overall you have a pretty chill time learning to be a decent DPS.
But learning to be a decent tank is much harder.
People need to be far more chill with others so they would try themselves on those roles.
But as long speed is king in dungeons (in general, not only in M+) and the general aggressive attitude towards it (you can see it in classic TW - You can basically skip half the bosses by shortcutting/ignoring them), nothing will change.
A part of needs to be adjusted by Blizzard by being more stricter with this in TW’s, only offering the rewards on all boss kills in the dungeon.
Yes the whole speed thing is also a problem but you can’t change that probably.
And then there are probably also a load of personal reasons why someone doesn’t want to pick up a a role.
Some don’t like the responsibility you have as a tank or heal.
And me for example I don’t like that all tanks have to uphold some ability.
I don’t like that for the same reason I don’t like to play BM
I didn’t enjoy tanking in the end of MoP especially much. Not much more than levelling a Prot Paladin during vanilla, where I pulled 30+ mobs and AoEd them down. Not more fun than TBC where some trinket was often used which healed you on each block. Not more than WotLK where you could do entire dungeons without a healer. Not any more fun than …
With M+ there’s a really big responsibility which lies primarily in the tank’s shoes; routing, pulling and ad-hoc decision making when someone butt-pulls something unplanned.
You want to fix tanking? Make sure that this responsibility shifts (at least partially) away from the tank.
Want to fix healing? Make sure there are significantly more heal checks. Maybe I’m just talking for myself, but I don’t want to DPS as healer, no matter how much I can put out. It’s ok to be able to put in-between, but I just want to see many more healing intensive parts (and not only due to group failures, of missing interrupts or what not).
Oh, and on top of that…make sure that the top 5% of all the runs are hidden in the APIs, so it’ll be harder to see what’s “META”.
I understand the thought process, and I don’t hate it, but I personally don’t think it’s the correct way to go.
Give tanks the power to control mobs and bolster the party defensively (they are in charge of routes after all).
Give healers more support power (bolster the party offensively), and have their cd be centered around staggering damage or pumping more healing.
Let DPS go full zug zug brain and let them stay as they are (with externals shifted to tanks/healers).
Do, however, add DPS checks do the DPS role isn’t the only role you can be absolute trash at and still get away with it. It doesn’t have to be that a bomb goes off and you die if the DPS check isn’t met, just have your dmg be reduced by 50% for 20 seconds.
The problem is that being a DPS is just way too easy, and you don’t really have to perform any good at all until around +16 keys right now. Meanwhile tanks and healers (in your average pug key) require a much greater performance to succeed. DPS being the path of least resistance will inevitably make it attract more players.
Are healers having problems keeping threat? 
Vengeance was a bad system. Tanks need bigger threat modifiers not more damage.
Back to the trinity:
Tanks have one of the highest threat modifiers in history atm. Threat is derived from dps though, so zero times thousand is still zero. They just need a dps buff, so that if someone lucky procs the dps gap doesn’t overcome threat generated and rip aggro mid pull.
Those were not players that played tank because they liked the concept of tanking, those were dps players playing tank and enjoying their damage output and reduced queue times.
You can, but it’s Blizzard’s interest to not change it, exactly because there will be uproar from the players that enjoy that speed. Just see what happened with the recent Timewalking Dungeon changes that make them last around 1-2 minutes longer than before.
The ideal solution is to change the way aggro works for tank specializations and decouple it from damage dealt. Make it so that if an enemy has been hit by a tank, it sticks to that tank unless actually taunted by another tank. Essentially have 2 aggro tables, one with every tank specialization that has hit the enemy and one with everyone else. And as long as there is at least one tank in the first aggro table, the enemy never checks the second table.
If ppl liked big numbers, everybody would be a healer! But while I mained healer for years, raid healing is a terrible gameplay, pvp healing is like bashing your head into a wall and m+ healing, while its fun, my main issue with healers in this game, is that there is no cool fantasy healer, I would be willing to stick to. Discipline is the only healer with some sort of neutral fantasy (results justify the means, void and sht). But what else is here? Some eco terrorists and god fiends? Meh, give ppl some sort of dark healer with cool fantasy and I think generally the popularity will rise.
But yes, I agree with the tank part. I think that tanks require a lot of studying and practice to get the strats right and adapt to the new ones later on. Its just too much effort and responsibility. Also I dont like the idea that there are always only 1-2 tanks that are preferred, closer to 1 tbh. I would probably play some DK because of its fantasy, but when was the last time BDK wasnt bottom tier?
Or maybe, just MAYBE, give tanks (idc about healers) more interesting specs/talents?
They all feel identical, with the same buttons, doing the same horribly boring rotation, despite the class and spec bloat (brewmaster!?).
DotC bears were THE shining light in the dark, only to fail so dang miserably, it’s sad.
And could Blizzard bite the bullet and actually give us a (permanent) pet based or battle mage tank (spec) already??
But yeah, playing all tanks just feel like alternating between one char changing its transmog instead of class.
I play healers and I like to dps as healers. It’s a skill impression when you can keep the group alive and DO dps, most of healers like it. Tanks literally do dps while tanking. This argument of yours is extremely weak
You are literally a monk??? Do you only press healing spells all 30 minutes in the dungeon?
You are probably right
But I don’t care anymore I accepted that I probably won’t ever have fun with a tank since all tanks have to hold up some short duration buff and I don’t like that
I heal, and my reasoning for staying out of LFG as much as possible is not because I don’t do dps… It’s because of the dungeon designs and a lot of peoples knowledge of it.
I watched a youtube video from AutomaticJack yesterday, where in one of the dungeons he said he was dispelling every 8 seconds (basically off CD) on one of the bosses, while having to AoE heal everyone… Whereas one of the other dungeons he said that you could go full dps build because he felt as a healer he wasn’t really needed.
What this does is, people have to play around this, which is good, it removes the autopilot brain from people… But… Thats not the reality. A lot of people just go to Icyveins or Archon and copy+paste their build and don’t change it. When the ele shaman then isn’t running cleansing totem or mage isn’t running remove curse etc. they don’t go “Oh damn, that was my bad!” nono… they go “Omg boosted healer???” or “Haha worst tank and route!”
I would say people care too much about their “big deeps” that the utility of their class becomes redundant and not really utilized.
Until people stop going full zugzug “I am flawless gigachad” and blaming healers / tanks for every bricked key, the issue probably won’t be fixed.
And have you tried tanking dungeons in a low level?
My friend started playing WoW and we did a HC dungeon… Because he wasn’t flying in pulling half the dungeon people flamed him with “Go play Delves noob” and ended up with him being vote-kicked for “noob tank”… People in M0 or +2 would tell him to go play HC, so what does he do? 
This anecdote has in similar forms been given by multiple people on forums / reddit etc. that is the tank / healer issue… The community.
100%.
The shortage has been induced by the community and they refuse to accept it and change their behavior
I would not say so, but it has a part in it.
In other mmos I have played, namely FF14, there is a tank shortage as well, and the community is a bit better over there in welcoming new players.
The role itself is also kind of braindead up until the very end game, and you still have to wait a good amount of time to get a tank in their version of LFD.
For as long as I can remember people avoided tank and healer roles, even if they are the easiest to play in games.
Exactly. And Im not saying tanks and healers are flawless, and people should start praising people who play the roles for existing.
But I truly do believe, that if people were willing to accept that sometimes keys brick and that you can’t expect everyone in lower content / content with no timer, to play as if its a speed run or just meet flaws with a bit more compassion more people would probably que LFG and more people would probably try the different roles.
That is why I enjoy doing keys in some of the communities I’ve found… Regardless of who messes up or how, people just tend to go “Oh its bricked”, shake hands, wish each other good luck, laugh it off and go next
To make people take less appealing jobs you have to pay them better and/or make them feel appreciated for doing the job.
Just like you will pay someone more to clean up the sewers than to sweep a room
Honest question in this discussion plus don’t throw stones at me.
Would it solve the tank shortage if we would make a tank that is ridiculous easy?
Like just passively tanky but you don’t have to play around defensives with just one or two big 3 minute cooldowns.
Then all you need to do is concentrate on cc and kicks and the route you do and such things.
Not all tanks but one beginner tank so to speak
then only that tank would be picked 
Imho all tanks should go back to being kinda “Blue dps” without active mitigation stuff to juggle with