Except, not every build has to have certain powers from the pools.
I would say that many players don't get what the Meta-players claim are mandatory powers.
I certainly don't. Probably the rebel in me.
My understanding is, if you don't have Hasten, Tactics, Maneuvers, Tough and Weave, you've gimped yourself.
I don't see it, really.
the vast majority of my characters don't have any of those powers, and they do quite well.
Agent Legacy (Grav/Time Controller) has been known to hold an AV a time or two. (8 holds/chance of holds)
She doesn't have any of the powers deemed necessary.
She also solos content at +0/x8.
Can she take on a Rikti Pylon solo?
Probably not.
But, I'm not concerned about being able to take on a Rikti Pylon solo.