There is another thread going on about how important art is in the presentation of an RPG and I answered, "It's not important to me at all, and in fact it might actually be considered a hinderance rather than a help in many cases."
And I can't help but wonder whether that's because I'm just imagining all of this anyway and so the art is literally in the way most of the time, rarely living up to my imagination or inspiring me better than I would be by day dreaming.
But this is in the light of this thread very obviously a perspective. I would imagine if you are a 5 on the scale then evocative artwork along with the text of your RPG is absolutely critical to your enjoyment.