They don’t need to, people have been buying Mac’s just to use it.

Maybe it’s in the works? Big corpo tend to move slowly

I think they're still afraid of getting egg on their face again. After the "headline re-writer" flop, they pulled way back. When Jobs ditched System x for OSX, his statement was something like, "I remembered that we're a hardware company, not a software company.", but that could have just been a marketing statement.