Obviously, I disagree. Emacs should have the same defaults on all
platforms, as much as possible. People such as myself who use Emacs
on multiple platforms become very confused when the colors they expect
don't show.
For users that use more applications beside Emacs on one platform
it's annoying when Emacs doesn't follow common system-wide look and feel.
I think there are more users that use many applications on one platform
and want all of them look the same than the number of users who use
just Emacs and switch platforms frequently.