1. Instead of putting every single spell, potion, and scroll into the hotbar, have "Potion", "Scroll", and "Spell" icons that open menus with the appropriate type. That is, you mouse over the "Potion" icon and a vertical menu of just potions appears. For spells, I'd want a menu of spell levels, and then sub-menus with spells of that level. And not just the icon but icon and name. I haven't memorized all those icons yet, and it's a PITA hunting for the one I want.
2. Find a reasonable way to prevent vendors from being looted of their magic items when you kill them. That's just cheesy.
3. Speaking of cheesy, it's too easy to take long rests, which undermines resource management. Need some way to gate that.
4. Make it possible to keep weapons unsheathed. I cast Light on my weapon to aid in exploration, except then the weapon gets stowed and I lose most of the benefit.
5. Create alternate rewards (read: magic items) if you overcome obstacles in some way other than killing. There's very little incentive to not simply slaughter everything. It would increase replay value if there were a good reason (besides "I want to read the dialog") to try things different ways.
6. Guidance cantrip: make it more obvious how it's working.
7. Sometimes I see that some of my characters have passed a Perception test, but then I can't figure out what it was they perceived.
8. Compass pointer so I know what direction the camera is facing. I would have thought I had played enough games to have a good mental image of how the mini-map correlates to the camera view, but I find in this game I often am confused about what direction I'm facing. I repeatedly run in an arbitrary direction then see what happens on the minimap in order to get my bearings.
9. Warlocks should be able to exchange invocations when leveling up.
10. Instead of making rogue Sneak Attack a clickable ability, make it work like Repelling Blast or reactions: if the icon is activated, then the rogue will automatically use it whenever it's available. And then have some kind of alert (floating text?) so you know when it happens.
That's all for now.