Your post is a whole bucket of wrong.

You have always been able to mix and match apps from a different desktop.

Vim and emacs are awesome.

Package formats have never ever been compatible, not even all distros that use the same format are compatible in fact. For open source software this is less of an issue than it seems basically the production of a package is 1/100000 of the effort required to produce the program itself and can even be done by individuals far less skilled than the original dev.

This means with only a relatively tiny additional input of labor a program can be packaged for all the most common distros.

I don't prefer unity but I think you bazaarly overstate the case.