Having all DLC and a Mulitplayer gamemode included is more than I expected. I'm pretty sure that if Sony alone had to make the decision how to release the game, the PS2 Pulse would not even have the DLC included. Fortunately SL had a finger in the pie.
Pure tracks could have been included as they need no recoding. Though, there's still the work you've to put into an reworked career mode etc.
Fusions tracks are wasted potential, true. But I didn't expect them to see them on the PS2 again (maybe on a future PS3 WipEout - Fusion HD anyone?) as they probably require a lot of recoding to get rid of the frame drops. Not to mention that the 3-tracks-per-environment doesn't fit to either Pure or Pulse. And then there is still much work left with Magstrips and re-arranging the weaponpads to fit the game physics/weapons. And of course: testing.