Originally Posted by
Syn20
Well, yeah. Once you know which powers work for you and your playstyle, you're gonna pick them every time.
The flaw in your logic is that you don't get any guarantee of any specific powers. You might have a run where you get the option of prime picks on every power choice. Other runs, you'll get absolute shit powers.
Not every class and spec has the same ease. Some classes have ridiculous powers - see the 1-shot videos from Mages and a few other classes. There's even a monk power that lets you jump and spam off arcane bolts - jump in certain places, and your jump time drops down to 0.2 seconds, meaning you just jump in one spot and win.
Many other specs don't have such powers. For example, one of the best I've seen as DH is being able to imprison a mob to MC it. Using that on some of the elites helps clear the floors, but that won't help you with the boss.