Maybe it was just my long day at work, but what you are saying here seems to not have much to do with what I am doing there...
You said you wanted proficiency to be increased from "+2 to +6" to "+2 to +10." Assuming you keep the maximum level of 20, that is having a half-level system. Exactly as 4e did.
Further, in 4e, ASIs are just a thing everyone gets at 4, 8, 14, 18, 24, 28: +1 to two different stats. (There is also a +1 to all stats at level 11 and 21.) This is completely unrelated to feats, and feats are, overall, quite strong in 4e--much better than 3e, though the best 4e feats are a small step down in size from the best feats in 5e.
Downtime activities and non-combat activities exist, have mechanical support (player authorship of personal quests, skill challenges), and there are "alternative reward" rules (from later in the edition's life) meant to give appropriate rewards without having them necessarily be
treasure per se.
4e gives you both of the things you specifically asked for, with pretty much all the details you've described, without needing any tinkering at all. They're literally part of the game already. Throw in the Dark Sun "inherent bonuses" rules and you'll even
legitimately make magic items unnecessary.
People keep saying stuff like this, and there are lots of reasons not to...
1. I don't own any of it.
2. From what I've seen of it, there is a lot of it I would probably not like.
3. I don't really want to take the time to learn a new system which I don't think will enjoy.
1. Fair. 4e books aren't expensive nowadays. $6-$7 dollars each on dmsguild.com. You can get official, watermarked PDFs of the PHB1, DMG, and the (much superior) MM3 or Monster Vault (I don't recommend the MM1/MM2, they have the older monster math which
works but is kinda grindy and slow.) That's still ~$20 you don't have to spend if you instead just play 5e, and I can 110% understand not wanting to spend that.
2. There's an awful lot of misinformation out there about 4e, and a LOT of people judged it outright wrong without actually reading. I would know, I was once one of them. Obviously, you have no responsibility to try it. But if you're getting a lot of people telling you this, there might be a
reason they're saying it.
3. Alright. Can't really find out what you like if you aren't willing to try, but nothing says you have to try new things.
shrug Just seems like a lot of work to keep repeatedly kitbashing a system that has a bunch of things not working for you.