Because this game has one tiny niche market that will buy it at any price.
They could release it at 9.99$ and it will bomb and only sell to the hardcore who would have bought it for 59.99.
If it includes all the DLC it's an attractive price and anyone who imported it probably paid that or more and didn't get the DLC. So it's really not horrible... then again this game is approaching 3 years old.
This is a pretty lame shmup, not worth $60 at all. I've played it at a friends who has it and an import 360. You're better off importing Mushihime-sama Futari or Espgaluda II which are both region free.
Maybe worth $20 if you're a huge shmup fan.
And don't expect to see virtual jigglies, it's very modest.