ruby mysql adaptor

I know that
the versions of RoR after 2 want you to use the C adaptor for MySql.
Is there some reason for this other than performance? Not all of us
need the highest performance solution (or we wouldn’t be using RoR) but
it is more convenient to use an adaptor bundled in with the system. Is
there any reason one could not bundle the adaptor from earlier versions
into a plugin and use that?