Text editing is certainly a small part of development, but if you're in a dev role where your job involves writing a lot of code, you actually are spending a lot of time in editing mode. I spend quite a lot of time in Vim now because I'm doing a lot of programming, and that's why it's worth spending the time to both learn Vim and configure it to taste. Most of the time what I need to get the job done is a great text editor, and Vim scratches that itch. If, for instance, I was doing massive code refactoring instead I can see why an IDE would be the right tool to use.