That's the thing, because there are so few, a true powerforward becomes invaluable.
No, I don't think it does necessarily. I mean, Cam Neely was the best power forward in the game in the early 90's. Pat Lafontaine was not the best small, finess player. Yet, I have them rated very close.
It's give and take. It's great to have a guy who'll scrap and stick up for his team mates, but on the other hand, it's great to have a guy who won't spend half the game in the penalty box.
While the prototypical power forward is a big, mean, physical winger with a great shot, they're almost never great playmakers (Lindros excluded). The great ones always seem to benefit from playing with a great centre, and vice versa.
My point, basically, is that power forward is not the pinnacle of hockey player evolution that some make it out to be. Brendan Shanahan is great because he's a great player. However, I think the "power forward" tag makes him look more valuable than he actually is to many people. There's a certain prestige attached to it that doesn't come with puck-moving-defenceman or playmaking-centre.