2D is a different type of skill to 3D, although they are related.

But I don't think 2D is simply better than 3D, so it is not the "logical" step.

Actually, pivot won't help you out in flash unless you use it until you're at least in intermediate (at least med inter if you like sub ranks).

Pivot isn't that hard to do angles and make different sizes for limbs. I can do it easily, you just have to know different tricks to doing it.

Flash is a good, basic 2-D program to start with.
I would do 3D all of the time, but 3D's max is hard to learn for me =/