I get your point, but nobody's interested in playing Quake 1 any more :). Generally speaking, with the recent/upcoming graphics-intensive games, when you're set to a reasonably high resolution and the pretties up, you'll have a hard time maintaining a steady 50+ FPS in the middle of an intense firefight. Which is exactly the moment when you need it the most, even if anywhere else you get 100 FPS. The lows are what you want to avoid.
Besides, the whole point of burning $550 on a top-of-the-line graphics card is the expectation of a performance level of X, and, well, you're going to feel ripped off when you find out that your store-bought $550 card, unlike the review sample, performs just slightly above the $400-ish one.