Yeah stash is definitely pretty bad, even after I was done cubing all my shit for the journey, I still had pretty much 4 full stash, and I was only playing one class. I mean sure I didn't need everything, but I wanted to keep all the WD sets, the jewelries I didn't cube yet, some legendaries/set for other classes I found, some items to reroll and obviously all the mats, gems, legendary gems and other various stuff. Playing multiple classes sucks if you play a bunch cause the more you play, the more you'll want to keep a lot of stuff for the classes.
I don't think the DB grind is horrific. It's additional loot for basically free. The rate of legendaries is good enough even without the cube with gambling and drops, but now you also get to target specific item types, which is super strong, so it makes sense it's limited, and it's really not that limited. Early on it is, but eventually it's like you get so much shit. In T10 you get like 20-30DB in a normal rift and you can clear them in 5mins easily, that's without sage, it goes really fast. With sage you can farm like 500 an hour or something, which is 20 legendaries, which isn't that much in general but the fact they're targetted legendaries and not 1/350 to get the right item is a huge deal. You gear up so fast now because of it, any more and people will basically be done in 2-3days with only ancients/better rolls as options to improve their gear.
I do see your point about not looting shit though, even if personally I don't care and always looted everything anyway. Worst case you just farm a bunch of whites and convert them, arguably faster if you don't mind farming whites for an hour or some shit to get a bunch of mats at once.