What if the PSP had had the touch screen to compete with the DS?  Would have the sales gap have been much closer than what it was?  I'm not saying the PSP did poorly because it did very well against the handheld giant Nintendo.  Now what if the PSP had the touch screen and the DS did not?  I know these are all pointless scenarios but it was just something I was thinking about in the shower lol.

Considering the cost of a touch screen in 2005, it could have made the PSP prohibitively expensive unless the specs were downgraded. I mean, the PSP could have cost $300 with a touchscreen, twice of the cost of a DS. If anything, I'd imagine that hurting sales.

As for switching the touch screens, that hurts both Nintendo and Sony imo. Nintendo would be left with a pointless second screen when they could have focused on power while Sony's system would cost over twice as much as its competitor.

Vita has a touch screen. How well is it doing?

It's not the touch screen, it's how the games use the touch screen. Do Sony make for the PSP games like nintendogs? Brain Training?

Good point.