Because the PAL8045 is much, much better. Quality and performance costs, but that being said the DragonOrb3 will cool a 1,4 T-Bird (and thus any Palomino) well, enough to do a moderate oc (I had mine running 1,533 stable with my old DragonOrb3 with 7000rpm fan).
The 1,4 requires an okay hsf but the PAL8045 and similar are only needed if you want to oc much, the DragonOrb3 is also better than what is aboslutely necessary but not as good as the high-end (both price and performance) hsfs.
If you don't want to spend much money and can take a bit of noise (the 7000rpm fan is as noisy as a Delta 7k fan) and don't want to make large oc's it's okay, but it isn't in the same league as the Alpha PAL8045 or Swifttech MC462A (to name the best) or the other high-hsf's.