Yeah, esp. those rears you mentioned. I got 120,000mi on the rear (disc) brakes on one car before they needed replacement, and another car I owned from new rolled past 120,000mi on the original (drum) brakes, and still had prob another 30kmi left on them when I sold the car.

 

2004 w/auto and standard suspension (i.e. "smaller" front rotors).
My commute is primarily freeway miles with only 3 (2 going, 1 returning) major (long downhill exit) decelerations from 60mph. I am not an agressive, nor late, braker. I have had my front rotors turned at 16K miles, replaced at 25K miles and replaced at 33K miles. All for "brake pulsation/warpage" and all under warranty. (Many thanks to Mazda and my local service manager for taking care of me without argument/complaint.) In this most recent replacement, the pads were replaced with a set that (reputedly) are better at dissipating heat. Time will tell.

For reference, my 1987 MR2 went 189,000 miles, before I sold it, without ever turning or replacing the front or rear brake rotors. (Same driving and commute pattern.)

So, I would agree that driving habits and the type of commute you have has an impact on the life of your brake rotors, but I would also have to say that the rotors on my RX8 have been a bit of a concern. (And yes, I am looking into purchasing aftermarket rotors from StopTech.)