Why remove material making your rotor thinner and more succeptible to warping if it isn't warped?

My stock rotors lasted 60-70K or so miles, when they became a little warped and caused some vibration under high speed braking I just replaced them. You can get quality rotors for cheap enough that I didn't consider having them resurfaced...for a little more money I can have new Brembo blanks and not have to worry about it for possibly another 60K miles.