you know that's completely not true. The Vita has a quad core GPU, exactly like the one in iPad 3. As you might know, the iPhone 5 is equal to iPad 3. iPad 4 is much faster than 3 though. At the very least, iPhone is just as powerful as the Vita. iOS has a huge advantage though as devs are more familiar with the OS. With the exception of Uncharted, games on Vita don't look that great. It has a big advantage with controls though.
1-Games must run on all the devices from 3gs to 5 so they are not optimized well for 4s and 5! Vita has an unique hardware.
2-Vita games are the first!At the beginning a new console has not the maximum potential!