I don’t see how this would fix anything. Also, I have zero sympathy for DPS players who would rather whine or try to reinvent the wheel just to avoid playing healer/tank.
Nothing until you try it.
Tons of pro and cons came up im this tread.
Many was againts solo que aswell.
There is a stuff like x only play pure dps classes cos thats their favorite for y reasons. They cant heal/tank with those classes.
But this is already where the problems start… there are people that can breeze through +5s with 590 gear, and there are people that fail in 2 with 619+, just as is the case with delves and torghast…
The difference being, delves and torghast can be soloed by reasonably competent players, m+ can´t.
So all it creates is an arbitrary barrier that, no matter how higg it actually is, will be demonized by half the community as too low because they keep wiping, while the other half says it´s too high and complains about being artificially held back by an itemlevel that´s laughably high.
Because the primary issue is that as soon as you make an automated 1 click signup to anything requiring no further effort, you get a massive influx of potatoes that never engaged with the the content before.
And the very next thing you know, the cries will come out for not only having to have cleared A dungeon on level X will be cries to have cleared ALL dungeons on level x and /or have x Rating before progressing “so people know what they are doing”.
And the actual result when teh dust setttles will then be: a new heyday for boosting communities, that will gladly carry people though keys for millions of gold just so they can queue in the random finder at 8s without ever having spent a talent point or used a single skill… i.e. exactly what we have today, but with even less interaction and chance to weed out obvious failbobs before the run even starts, because you´re all in the instance already and the timer starts in 15 seconds.
Hmm… Take deserter now or farm repair costs? You have 5 seconds lefto to decide, because less then a week after the system is introduced deserter will be upped to 1 hour after the timer starts as a result of public outcry over trolling /griefing /people seing the writing on teh wall and saving themselves 5000g of repair costs. 
See also the whhole drama with rune dungeons in Wrath Classic. Exact same problems, discussions, and failed “solutions”, just in a different game client. 