Vim has great plugins -- but expanding it is often best left to experts. I have a pet theory that part of the reason for the high quality of many vim plugins is the horrors of writing them (and of course, tpope). Most Vim users are simple, "off the shelf" users -- they use plugins, but they don't WRITE plugins and they often don't radically change the environment (it still feels like vim, as expected). Vim is a good editor that works great with other tools.

Emacs is more -- of its own things -- lots of people write little bits of elisp to do their bidding, and the "plugins" can completely reshape the editor into an IRC client... a mail client... a media player ... a connection to spotify ... etc. It is a wild crazy world powered by elisp.