Do you think there's something we can do to encourage more people to add touch controls? Also I think Tom was going to add a special category for touch-enabled games.
A separated category is a good start.
I think the best solution would be to show little icons which will "tell" things about the game. If it's iPad friendly it will show an icon. If it's not the icon will show the icon in gray with a strike over it. The same goes for Android, etc, etc.
As for my proposal, I guess I didn't explain well.
My idea is in that direction. I was sure that since we're talking about an interpreter it would be easy to add 1 layer of a keyboard/mini-controller to arcade games. I guess it was a crazy idea.
As for the "how to encourage" question, that's a good question. In the long run games which are accessible to more machines will float to the top. In the short run it's important, as I see it, to add "Does your game support touch screens?" question to the arcade upload procedure.
The uploaded can also check check-boxes for different machines. This alone will make them think "Hey, my game only supports PC and Mac and not the iPad, Android, etc, etc."
A special badge would also help (Something like "The Touchy Badge" :)
Also, I don't understand why there're two objects - Mouse and Touch. If the touch can simulate the mouse why not unite these two into one object. This will allow mouse events as well as Touch events. The creator will have to know what's the difference between these two but it will cover 99% of cases without duplicated code.