I'm not the one to ask -- far as I know, it's just the way this sort of thing is done! I think it has something to do with keeping the game in the news and on the PSN front page a little longer, maybe? I dunno.
Either way, I passed your feedback along to the rest of the company at yesterday's game meeting, as you brought up some good points. I suggested we re-evaluate this DLC release strategy for future titles, and it sounded like we probably will. Not saying we definitely won't release DLC for other games like this, but we'll at least do a bit more due diligence in questioning the approach before simply settling on it.
Great news. I'd love to see the already-released DLC day one (especially the free stuff!) because honestly very very rarely have I gone back to a game for DLC especially cosmetic/minor stuff, that I especially want day one.
Borderlands and Driveclub are the only ones to get me to keep coming back so far. But I've bought cosmetic and character DLC for Neptunia day 1 and would have preferred to do that for Disgaea as well but NISA also dripfeeds