A agree in some points and disagree with some.
AP as an reward for everything was a good addition. You always got atleast something. AP as an power creep that you had to farm like an absolute moron was not a good addition. Where to found middleground idk.
Titanforging was a nice dopamine dose when it procced. It didnt had to be remowed completely…just capped so that items didnt proc 4 tiers higher than where they dropped.
A do think it should come back as an proc, because it would be a nice addition to current upgrading system where it would be clearly capped at max upgrade (like 8/8 or hero 5/5 etc.) and could proc anywhere in between.
I know you didnt mention this, but i do believe that bonus rolls should come back. It didnt hurt anything and it was nice additional chance before you got locked out for a week. I dont underatand why they even deleted it.
What i personaly believe should come back in some form are Class halls, class campaigns, and most importantly artifacts. Not the power and talents that came with them, but the socket system and the apearances.
Class halls and campaigns and basicaly all of legion main content were and absolute amazing stuff for casuals. Imho.
Apearances with different versions from different contents, achievements etc were a slam dunk aswell. Because lets be honest…all weapons since Legion looks like an absolute 
anyway and everyone mogging them to legion artifacts. This game needs a huge step up in weapon cosmetic department and the best way to do it was legion artifacts including the ilvl raising by socketing the relics that dropped instead of an actual weapons. Aside from the talents, spells and ap grind that came with it that was a nope for me.
Legion legendaries were nice too…when you could buy a specific ones for currency at the end. The item effect were often gameplay altering which is a nice little content on itself.
Next on the line for me is great vault. While an billion times better than legion and bfa…it still needs an polishing. They should just go all-in at this point and accept it as an main source of gearing and gear upgrades. Meaning that some sort of bad luck protection should take a place aswell as some sort of “slot blacklisting” where you could set one or two slots that you dont wanna an item for, or the other way around set one option of the three would guaranteed be a weapon for example… Something like that.
I do have a more stuff i would like added to the game, but these are more controversial that the above.
For example i would love gear like corruption back in the game, i personaly feel like it was the most brilliant kiss/curse, fun and intteresting addition this game has ever received. It was also overpowered af to be fair. But because the aquisition was implemented horrendeously at the start, they completely rulled it out as an failure under the pressure of negative comments. While all it needed was clear and not random method how to get them and tuning. Aswell as the negative effects. This feature disapearing to the “failed” void making me sad to this very day.
I would also like reforging back, proffesion bonuses back, million sockets in each item back, meta gems and socket colour bonuses back, enchants for every slot back, more slots for rings (like why not have 4-6 rings?), more diverse set bonuses, pvp set bonuses, 2v2 and rated bg solo q, more stats etc etc …i could be here all day.
But the general issue and main point which makes all of the above pointless if done wrong…is classes. If the class and character you play feels like , then no amount of content will save it. They have to nail classes, changes and gameplay first for the expansion. Not the million reworks in middle of a second main content patch of the epxansion.
All the nice features that comoletely dissapeared in the name of dumbing the game down for masses …and it still failed.
All just imho. Ofc.
