The fact that you can’t feel an analog joystick or tactile buttons on a touchscreen device isn’t one of those constraints you should fight against. Yes, it means you can’t port Halo or Street Fighter to the iPhone (not that people haven’t tried). But we already have those games. When the Xbox 720 and PS4 come out, we’ll have even more.
iPhone and Android devices offer new possibilities for game input: acceleromoters, GPS, cameras, multi-touch screens. Use those to kill aliens or punch people. Rage HD did a wonderful job by embracing the once-reviled rail shooter genre. Plants vs. Zombies is even better on the iPad, its anti-zombie gardening feels real when you touch each square. Embrace your limitations, artists!
Conversely, imagine how hilarious the world would be if touch games came before controller games. We could buy the Zeescreen®, a 60" widescreen pane of glass you mount in front of your television. Play Angry Birds on your Xbox, controlled the way it should be.