I didn't think they would release that model as new guardian jetbikes. My reasoning is that, though the guardian jetbikes would be cool, they would not go with the Spears, Farseers or Warlocks on jetbikes. Hard to hold a lance, spear, or sword when laid over the body of the bike like that.
I think the biggest issue with the bikes was the transition from artwork to sculpt. The original pics had the guardians really "sunk in" to the seat, with the head just at the top of the seat back. Very laid back and very cool lookin'.
However, the model ended up having biks a bit too small and guardians that looked more stiff and straight, rather than laid back into the seat. Were the same bikes a tad bigger on the back and the front, a more laid back guardian body could be sculpted to fit in better.