Depends on the type of projects you are doing. If you are just editing home movies, then no, you don’t need Studio. But if you are out there doing custom videos for money, then quality should be an issue to you. I use the heck out of the other applications.
But I think you can upgrade from FCP express to Studio, so that might be the initial path to take. But yeah, Express will do cuts and dissolves if that’s all you want.