Well, some say straightening a rim is a definite nono, a sacrilege against the cycling gods etc etc. I've done it on numerous times, and although those rims have only gone on beater bikes(hence limited mileage) they seem to be doing just fine. At least far better than they did when the spoke tension was all over the place.

I bet some people would be amazed/horrified if they'd ever see how and how much force that has to be applied to counter-bend a rim. I've laid rims across a 2x4 on edge and stood on them several times.

If the sidewalls starts to flare, then that's bad news. But remember that when the spokes go back on they will all try to compress the rim to a smaller diameter, so the joint will usually close up quite nicely. Again, IME to no significant degradation of rim strength.