But most Vim addons seem to be written in Vimscript, and porting them to another language (which?) is a lot of work for little practical gain (for many/most addons).
Okay, I did a quick grep through the documentation of my distros current vim installation and came up with support for Lua, MzScheme, Perl, Python, Ruby and tcl.
So yeah, there are lots of interfaces to chose from.
But most Vim addons seem to be written in Vimscript, and porting them to another language (which?) is a lot of work for little practical gain (for many/most addons).