Can't wait for them to not put it on the one machine that would make them even more money
The profit margins are far lower (smaller market + higher development costs due to increased labour), which is partly why PC Game Development is unattractive to the AAA market which wants to make safe bets.
The day that Apple rules the PC-sphere and all PC hardware/software is standardised, then maybe you'd have a point. That's not going to happen, though.