I used to work on desktop apps doing interesting stuff with large and/or soft-realtime data. Now I am working on a Ph.D. in CS. I decided I would not be happy in the long term unless I'm doing research-level work. Even though I was developing products much more interesting than the typical CRUD app, I was still spending lots of time on GUIs, undo systems, file IO, etc. I want to avoid that kind of work as much as possible in the future.