In Reach, if you didn’t control the power weapons, you practically lose. Is it the same with Halo 4? I don’t have the game yet, so I don’t know the answer.
With ordinance drops, this isn’t a problem. However, I know Slayer Pro doesn’t have ordinance drops, but I haven’t played enough Slayer Pro to determine if that’s a problem.
Are you asking if power weapons are still powerful?
Then, yes, they are. 