1) That sweet sweet feeling of feeling different. I've come to accept that part of the reason I use linux and vim is I derive some satisfaction from being "hipster". But not enough to say, use gentoo :)

2) Simplicity. Even with all my vim plugins, I never have issues with "IDE hogging all my ram" or "intellij crashes when loading a working set including this commit" (it worked for me...).

3) Ease of access. When remoting into my boxes, I can just tmux attach and continue editing where I left off, even on a shitty connection (using mosh). Very useful on train/conference wifi.

In the spirit of your first clause, these are personal reasons that work for me. I have not listed the cons, of which there are many, and don't expect my reasons to apply universally.