This is a super dumb example, but I hate that scrolling is tied to cursor. Like if I'm
gasp using the mouse to scroll through a file in emacs, the cursor has to stay in the viewport. If I scroll past the viewport, the cursor moves to the viewport. In IntelliJ (which has such good emacs keybindings I can use it for a lot of my work), the opposite is true: when I scroll away from my cursor, it stays there and when I start typing again, my viewport moves
to my cursor
not vice versa.
It's a small thing but it shows emacs' age. When emacs was written, GUI cursors weren't a thing. Scrolling wasn't a thing. Of course the cursor and the viewport would be connected. There wasn't any other way to move the viewport. Basically emacs needs to be somewhat GUI native.
Emacs should also be more discoverable. It's hard to incrementally learn key commands. I hate that the default for M-x is just a blank line. It's really intimidating. Having some sort of fuzzy search/history like Helm makes M-x so much easier to use.
Basically emacs needs to get UI and UX people to give it a refresh. Nothing outlandish, just get it into the 21st century.