It seems that Natural Attacks got a significant upgrade in PF with the changes to natural attacks. They also seem easier for PCs to get access to.
Is there a compelling reason that these changes were needed, is there a significant reason not to go back to 3.5's one is Primary the rest secondary natural attack rule?
No, I'm almost positive that in 3.5 if you had a creature with a bite/claw/claw natural attack sequence with a BAB of 5 the attacks would be made at 5/0/0 because the bite would be primary and the claws would be secondary.
In PF a bite/claw/claw sequence at BAB 5 would be made at 5/5/5 because in PF both bite and claw are always primary attacks. If I've been reading PF stat blocks/rules the wrong way all this time let me know.
This makes creature/PCs with multiple natural attacks potentially much more deadly in PF than they were in 3.5.
Natural attacks did get an upgrade in PF. Previously the first attack was the primary one, and the latter were not. This got changed.
It did make natural attacks better. That much is clear. But a compelling reason not to switch back is that you would really screw up the CR of alot of monsters. Pathfinder reorganized CR and standardized the math around monsters. Changing how natural attacks work would dramatically effect how dangerous quite a few monsters are.
The CR is a good point, thanks, and something to keep in mind when converting 3.5 encounters to PF.
I now wonder if a change should be made to PCs, Animal Companions, Eidolons, and the like who are using natural attacks.