The only issue I have of not changing the rotors is that they can get machined a bit thin (but within spec) and start warping sooner rather than later.
I rather change them and eat the cost up front than pay to have them machined and have do it again in a year or two because my steering wheel starts to shake when braking because the rotors got hot and warped.
This maybe more prevalent with German sedans, but it did happen to My Expedition before. After that, I just change the rotors whenever the pads need to be replace, which for me is rare since I am generally not hard on my brakes and tend to last a long time.