I believe the whole point of the WoT is not Good beats up Evil with a stick and wins. It will be about the emotional, psychological and spiritual states of not only the main characters but the masses.

I totally agree with your assessment of the Asha'man and their role, however I see it their as a contrast to Perrin and gang. Each mirrors a facet of the Dragons personality. Like King Artur Rand is tied to the land/people. The physical battles are just symbolism for the true battle within.

If Rand were to create a weave like the one he uses at the start of tSR and destroyed all DF and shadow spawn the battle would not be won. People would still be in the same current vain and corrupt cultures. The prophesies foretell that he will break the nations, not the forces of the dark. It is the whole fight fire with fire deal. We see this happen with Rand, especially at the wells. He becomes the same as the shadow. Perrin was there to be a hold to his humanity, he didn't succeed fully, so he may not appear to be the important character here. But he is every bit as important as Taim and the Asha'man, they both are representing the two facets within Rand that are battling.

I say he is important because if the Perrin facet wins then the LB can be won, if not then the dragon winning will be worse than the shadow winning.