Emacs addon packages--compile upon install?

[pfaffben@pilot.msu.edu (Ben Pfaff)]

This morning I uploaded a version of w3-el that doesn't compile upon
installation--instead, there are separate precompiled packages for
Emacs 19 and Emacs 20, plus a shared documentation package.  I see
this as a better way to go than forcing the end-user to have to sit
through a long compile (it can take 15-30 minutes for w3-el to compile
on an older machine).

I am trying to remember the rationale we had for making Emacs' addon
packages compile when they install themselves, and I can't remember
it.  Perhaps you can remind me.

Unless there's a really good reason, I think it might be better
strategy to more towards something closer to the w3-el model, i.e.,
one binary package for each Emacs version: for instance, bbdb-e19,
bbdb-e20, bbdb-x19, bbdb-x20.  There could be a bbdb-common or
bbdb-doc for shared files.

Comments?