Why aren't iPhone and iPad games playable on Macs?

It seems like such a simple idea that'd please customers and provide a much greater incentive for them to purchase games: Why not make iPhone and iPad games playable on Macs?

By doing that customers could use real buttons to play their games. Plus, it adds another dimension of value to each purpose. And more still, I don't imagine it would be that hard. Apple has an iPhone simulator included in their SDK so I don't imagine they'd need much more than that to allow us to play the games.

Macs need a kick start when it comes to games and I don't see a better opportunity coming along than that. The resources are too great to bring big, original productions to Mac. Valve is leading that push right now. But why not just take advantage of what's already there?