The original release was almost exactly like you described, and caused problems where there were very strictly limited supplies of absolutely everything. Remember that DivOS has no respawning enemies with the exception of enemies that spawn during a fight, which don't usually drop anything or grant exp.
It was a system that practically required savescumming. Want a particular spell? Gotta savescum the merchant till he has it. Want even half-decent loot? Savescum known good chests until they have something useful.
In the original, I felt like merchants almost never had anything good. I saw maybe 5-10 legendaries. 1-2 divine items (at higher levels, at least) per level per merchant would get you more like 40-50 divine items if you start seeing divine items at level 10 and there's 3 merchants that can potentially sell them. If merchants now really sell several divine items, you must have a pick of 100+ divine items from merchants alone. This is bad because it dilutes the experience of divine items and makes them feel less powerful if merchants are selling tons of them. Especially if it's still relatively easy to get a lot of gold, if not necessarily quite as easy as it was before.
Lots of games have a limited supply of loot. You should be able to find good loot and have a pick of items, but if you can get pretty much any items you want through merchants, it's harder to balance the game and the loot experience is weaker.
Lockpicking is useless, not because it's not required for some chests (it never should be), but precisely because the keys are never far away. Lockpicking could be useful for traps though?
I disagree: I think there should be chests, maybe even doors, that can only be lockpicked. In an effort to make everything accessible by all characters, abilities like lockpicking can become useless except as a minor convenience. Probably the best way to go about adding things that can only be lockpicked would be to add a quest that you can only find if you have lockpicking (say, an NPC asks you to unlock something for him) that leads you to buried treasure that has to be unlocked. People without lockpicking wouldn't be running into chests that they can do nothing with if they can't lockpick, unless they just happened to dig in some random spot. Some of these chests should be buried behind hard boss fights, so lockpicking would in a sense provide an extra reward for killing bosses
The rest of your post mostly highlights the fact that ability bonuses on loot are way too excessive. Trait bonuses also reduce the need to invest in points. That you can get 8 points in lucky charm without investing a single point is absurd (though it is pretty inconvenient to don all your luck gear just to open some barrels.) I think Larian has made a lot of these abilities useless because they're so easy to acquire. If you had to actually invest 15 ability points to get 5 points in lucky charm, maybe finding a single +1 lucky charm on an awesome piece of loot, it'd be fair for lucky charm to give a small chance for divine items or even pull from a pool of unique items.
