[slurgfest]

I find that Vimscript tends to be faster than the other languages in many cases, for one reason.

But probably the #1 reason to write a plugin in it is that your users don't have to run some flaky Makefile/Rakefile or install system dependencies in order to use your plugin.

This is most of the reason I jumped ship from Command-T to Ctrl-P as soon as it came out.

I will concede that Vimscript looks grody and I wouldn't write non-editor software in it, but it is really a DSL for configuring an editor on the fly, works great for that and doesn't really hold a huge number of shocks for someone who can handle things in the range of C, bash, etc.