Pet traits
I understand your (and plenty of others’) point of view on this subject, but I couldn’t agree less. The ranger’s special mechanic is having an animal companion. It’s there 100% of the time and is always part of your build. Accordingly, if I want to make a build that focuses on skirmishing, I want to be able to also enhance my always present special mechanic rather than completely neglect it.
Centralizing pet traits in the BM line would essentially force every ranger to invest 30 in BM in every build just to make the pets better than mostly crappy (I realize many of you feel like this is already the case, and I’ll just agree to disagree with you to avoid going off-topic). As it is now I can enhance my critical strikes and my pets at the same time, for instance. Mixing it up as they have is how you ensure that there is build diversity.
Likewise with traits that add offense in a defensive line or vice versa. Being able to compensate for lost damage from adding points to vitality, healing, or toughness is key to creating viable builds outside of min/maxing.
Plus you can avoid taking any pet focused traits if you want to. That option is always there.