well its actually been out in arcades for over year or so, that's why it looks kind of dated.
besides SS6 came out a while back too. i think they just wanted to cash in on the success of SF4/SC4 etc that they knew would be on the way.
btw if you haven't picked up SS Anthology just came out and has a MSRP of 14.99 (Not the best job but standard for SNK. it contains 1-6)