For some (entirely irrational, I'm sure) reason, the idea of constant and automatic deployment of my dotfiles across all my boxes gives me the shivers. I like that extra bit of control I get from doing it with a git repo.
Same, which is why I git repo them as well. It's mostly a nice way to keep a few bits of code in check, plus handy for quick private repos without needing all the nice stuff from GitHub/BitBucket.