Shop is terrible. They need to revamp the whole thing. I am making a post about it.
Some key highlights:
Make alternate skill effects. POE proved ppl love these. Like Dark energy ice shards, Zombies instead of skeletons for necro, Whymsywind rainbow colored whirlwinds. All these are cosmetic changes and do nothing to affect gameplay.
Also make cosmetic armors / weapons pop and stand out.
Make themed content for builds. Your lightning mages probably want lightning themed cosmetic sets. Your poison rogues probably want poison themed cosmetic sets. ECT.
Some awesome mounts.
This isnt hard stuff to figure out. Devs should know what works and does not work by now. I can tell you with 100% certainty that the current mostly gray bland cosmetic shop is not selling well.
The players want to spend money in shop. We like to celebrate achievements like getting to 100 and then buy stuff. The issue it is slim pickings in there.