I think a part of the reason Sony has shown so much support for independent developers is to send a message of how easy development can be for their platforms. Sony has clearly responded to the past generation's criticism of the cell, and what better way to show that their system is easy to develop for than by having small developers easily creating content for their platforms. Ultimately, Sony is bolstering new talent by making this independent push, which I think is a good thing for the industry. Hopefully this encourages some of the Japanese developers (who don't operate on AAA budgets) to return to consoles from handheld-only development.
In regards to the topic, it's clear that there is a lot of AAA development for the PS4, so it's not as if the PS4 is only focusing on independent development. As for the Vita, I think Sony is trying to finding its audience and sees potential in bringing indie titles to the handheld space, and honestly, while I have a ton of indie games on PC, I think many of them would fit nicely on a handheld rather than on a monitor or big screen.
