Some very strange choices there. Cilic has no place there even when his FH is the wildest it can possibly be. His FH is a major weapon. Isner's FH is as good as his movement will allow it, i.e. when he gets into a position it's a solid enough shot. Youzhny? It's not as good as his BH, but what the heck is he doing on this list. Roddick and Monfils like to push a lot, but their FHs are not exploitable in a major way.
Well, the fact that those players are in the poll doesn't necessarily mean that I think that their forehands are bad, but I tried to choose the players who are perhaps in a second tier within the top 20 with respect to their FHs. What I mean is, I think the 12 other players who are not in the list clearly have better FHs than those listed. It's all subjective, of course.
I agree with most of what you said - though I think it's exactly those factors which limits the utility of those players' forehands. Cilic has problems with consistency, Isner is restricted by his movement, Roddick doesn't really seem to have a weapon in his forehand any more, etc. Youzhny's forehand is decent - his is probably the best of those in the poll.