There's a place for both rep ranges. Wendler pretty much hits the nail on the head with a tiered approach....so your top sets are 85% week 1, 90 week 2, and 95 week 3.
To answer your question directly, I ask you another (fairly obvious) question. Let's say you are given 2 months to improve your 1RM on squat and deadlift by 40 lb each, or else your entire family will be killed. What rep ranges are you going to train in for those 2 months?
IMHO, improving your 1rm will do more for your 8rm than the other way around; however, the optimal way to increase your 6-8 RM is to train in the 6-8 rep range, while the optimal way to increase 1RM is the lower rep ranges. The thing about a 1RM is, to lift more weight, it is something your body has never done before...ever. Your nervous system has to adjust to the new stimulus. You need to push that at some point.
God, I hope I made some sense here. It sounded good in my head =/