There was also a crazy inflation of creating more and more bat characters, so it was getting harder to compete with all the others on the limited spotlight available.
Personally, while I prefer Tim to be a college student that balances school, dating, discovering himself as queer and solving crimes, I think he mostly needs a writer who's passionate enough about him and has a clear idea of what they want to do with him. If the idea is good enough, the codename isn't that important.
Tim didn't have a solo for ages, but judging from FS he may have enough fan base to try a mini that could explore his story further.