There is a fine line when chosing between graphics detail and game play. If the detail was much higher, you would have a lot more people warping. This would screw up the game play. Once over the eye candy the detail isn't noticed much anyhow. I don't care about the detail of the trees etc because I'm not here for sight seeing. That's what FSX is for.
Just wanted to point out that frame rate and warping are not linked. Maybe more people will complain about low FPS, but the skies won't be any warpier for those with more capable computers.