Because a lot the games on the PS4 have been on PC or PS3 for ages. I know for some indies are a big deal, but I'm not spending $400 on a machine only to get games I can play on the PC. The PS4 simply doesn't have enough exclusive AAA experiences at launch. When I'm showing friends what the device is capable of and trying to get them to buy the machine, it won't be Doki Doki Universe and [Insert Indie game here]. It will be for Titanfall or Halo, Infamous or Uncharted. Indie games while good just don't typically offer experiences in the scale that you would get from AAA games. I'd trade half those indies and f2p for another Uncharted and other big IP at launch. I know my opinion is an unpopular one.
AAA titles are coming but you know... having the smaller and mid-tier titles to fill the gaps in between is never a bad thing. And hey.. if you looked you'd see some of those smaller titles do in fact look quite amazing as well.