Belatedly, in the spirit of trying to use Usenet more...!
Whether it makes sense for any particular game is kind of up to the
game. Speaking as a programmer, it is nice to have a well-defined
interface, programs that take the time to think about how to turn the
functionality into a clean API are usually better programs.
Also, depending on a lot of other things, in some cases having a proper
module loading system might make it possible to write mods in a
different language than the game itself.
No idea whether you were still interested in this, but hey, you shouted
it into the void and all that, so I figured I'd try.
Irene