Brood War is a game, not a hardware expansion on an existing console. Big difference.
The Wii Fit board is the most popular hardware expansion of all time and look at all the support that got. No hardware expansions will ever come close to a new console release.
Sorry, do you think I didn't realize that when I posted the example?
Of course it's a game and not a HW expansion, of course that's a big difference, but it doesn't change the fact that it's equally applicable in the discussion of adoption. Some people made use map settings only made for the classical version, but they were few because BW was so well made that everyone adopted it.
Another example is Diablo Hellfire. It's not considered part of the canon because it was made by a 3rd party and wasn't officially backed up. This all supports my "push" argument, regardless of the differences you mention.