According to Stoptech's article actual cases of warped rotors are extremely rare! The link is available in one of my previous posts. Read it yourself. EBC backs up Stoptech's article.
And I don't think that the problem occurs because the sides of the rotor don't wear identically. It happens because thinner spots appear on the rotor due to excessive run out.
I read both articles long ago.
Drive a car with severe pulsation, then chuck the rotors up on a quality lathe.
As the lathe turns, you'll want to ease the bits in, near the center of the rotor, until they faintly touch. You'll hear a little rythm as the bits come into and out of contact with the rotor surface.
Move the cutting head in to the edge of the rotor surface (torwards hub). Turn the bits in another thousandth or two, and run a quick fast cut.
You will likely see that only part of each side of the rotor gets machined. There will be a shiny patch that the bits were not able to touch as the rotor spun. This patch will likely not be in the same place on both side of the rotor.
Is that not what one would define as 'warped?'
Again, the simple thickness variation is more to blame for what you feel in the pedal (or the whole car, if it's bad enough). But 1) it's still splitting hairs to say that's not a 'warped' rotor and 2) the rotor probably DOES have some warp, anyway. (edit: again, defending on how you define warp.)
I don't even generally disagree with those articles; the Stop-tech one is very familiar and has some good info. But all that really needs to be said is that vibration under braking is generally caused by some kind of
quality of misshapenness that the rotors have acquired. And since the industry standard is to just say 'warpage,' there's no point in sounding off with an 'Actually...' comment.
The more important thing for people to learn is WHY rotors...
become misshapen. And that, in a word...okay, two words...heat and pressure (does 'and' count? okay, three words).