Because the way I see it, the exclusive AAA/AA roster is pretty much even:

PS4 AAA/AA games announced:

• Infamous: Second Sun
• Driveclub
• Killzone: Shadowfall
• The Order: 1886
• Knack
• Deep Down
• Blacklight: Retribution (console)
• Warframe (console)
• PlanetSide 2 (console)
• Diablo III (console)
• Final Fantasy XIV (console)

Guarunteed/likely:

• Naughty Dog game
• Santa Monica game
• Media Molecule game (and no, not this; they have an unnannouced project)
• Gran Turismo 7
• The Last Guardian

X1 AAA/AA games announced:

• Halo 5
• Forza 5
• Killer Instinct
• Dead Rising 3
• Ryse
• Sunset Overdrive
• Quantum Break
• Project Spark (console)
• Titanfall (console)
• Zoo Tycoon (console)

Everquest next under guaranteed for PS4.

Aside from Naughty Dog and (maybe) Polphony Digital, Sony's first party studios can be accurately classified as about the same as your typical indie developer.

le le epic trolling XDXDXd!!!111!1

Lol, what?

Santa Monica = indie developer?

It's a really strange phenomenon, I think. The more downloadable games you add, the more some people tend to say that you're focusing too much on smaller developers--even if you're adding more big budget games at the same time.

Announce 10 AAA games and 5 indie games = awesome!

Announce 10 AAA games and 15 indie games = what the hell, why so few AAA games?

It's almost comical.

Indie devs are the future of the industry. Many of the top developers in the world today started life as relatively small independent developers that gradually grew with each success and found big name publishers or were acquired.

For Sony, the big success stories are investment opportunities for the future. Find a successful indie dev and bring them on as second party; if they're really successful then perhaps even acquire them.

Aside from one IP, Santa Monica's output has been purely indie content. 

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.