I feel like they are using up some of the lesser known characters as free DLC. Honestly not a lot of people are aware of who these characters are except for probably the hardcore PS fans.
This way it entices more hardcore people to get the game ASAP as they are only free for a limited time, while they can save more well known characters as fully paid DLC later on when the install base has grown.
This also gets the game some good PR, because a lot of people get pissed about DLC coming out so fast after release. By making it free they will get a big thumbs up from the gaming community while still having some very soon-after-release DLC.
Not a bad plan.
Platinums: Red Dead Redemption, Killzone 2, LittleBigPlanet, Terminator Salvation, Uncharted 1, inFamous Second Son, Rocket League
