2) Useless gold. 5e doles out gold with very little purpose.
--the new bastion rules and perhaps some new item buying rules might help address this, jury is still out.
3) CRs are very poorly mathed out. The current CR system is designed for absolute newbies who want to play the game on easy mode, and once you get to ~5th level the CRs just don't work. Now CRs are always a bit of an art than a science, but high level CRs are a joke compared to what high level parties do. Considering the wealth of raise dead/come back abilities at high levels, fights should be MORE deadly (with the "easy mode" being easy resurrection) rather than just cake walk battles.
--WOTC has suggested that a lot of monsters have been retooled to better fit their CR, so probably the biggest hope for 5.24 on this list.
4) The game still does not well support a "small number of encounter per day" model. This is 2024, dnd has moved out of the dungeon and has now embraced a much larger world. Many groups do lesser combats in favor of more roleplaying, or do more overland travel type games where 1-2 encounters a day (or even less!) is the norm rather than the 6-8 encounters the game is balanced around.