Vita launched with Uncharted (3rd strongest IP Sony has) 2 lower tier IPs Sony has - HSG, Wipeout and 2 completly new IPs in form of Little Deviants and Reality fighters.
In next months they followed with Unit 13, Resistance and Gravity Daze.
And they will release also Sly , Smash clone and LBP all in first year on market.
they really needed to show that they had everyone actually on board for it. even if it meant little ol' sucker punch doing the work for sly or some vita game instead of naughty dog doing the work for a vita game. why care about a handheld none of the bigger teams believe in?
although i think it says more about those teams than it does the vita, that games aren't coming out from their studios for the machine