We, at JDI, are used to working in vi. When we started 11 years ago, most IDE's wheren't existant, and with 3 people with their own OS and configuration developing locally wasn't an option. So we just shelled in, vim'ed all of our files, and created nice things that way.
Today, when the compay has grown, this isn't an option anymore. People want an IDE, mainly for code completion and debugging.