It's a question of training outcomes. You can see the big squatters in WL becuase they don't - generally - get pinned by the weight, however a lot train for the 'bounce' reflex to help recovery (the guy from Catalyst Athletics and Charles Poliquin...) from the clean/snatch. But again, you can't be a decent weightlifter if you can't squat properly (to FutileBreadMAchine's point).There are numerous stories of weightlifters who couldn't squat what they cleaned because of the lack of bounce reflex (this also applies to what the bar is doing, but that's a different discussion).
Klokov also suggests squatting s-l-o-w-l-y because bouncing allows people to squat more (Milko Tokkola, that US/Brazilian lifter that got busted...) and may not be a true reflection of how strong somebody is (dealing in semantics, but hey).
Personally, somebody (in my book, but I don't have the cache of Duffin or Ripptoe...) can squat as fast or slow as they like provided they understand the caveats of both and they don't squat badly (which is critical, irrespective of speed).
