So is oversteering normally the rule for large aircraft, or the exception?
The KSFO restriction still puzzles me. The gates might be a tight fit, but surely the taxiways are not, and if you stay on the centerline, the rest of the aircraft is more likely to drift away from it than if you oversteer. Unless the taxiways are exceptionally wide, this would increase the chance of running off the pavement or squashing a taxiway light. I don't see what KSFO gains from the restriction. Maybe it's one of those California things.
I have the advantage of being able to watch my aircraft from above when taxiing in a simulator, and as you point out, the body of the aircraft as a whole stays centered considerably better with oversteering than without it. The same would be true of any vehicle, presumably—I notice that city buses do it all the time.