There is an upside, and that is that you never have to deal with ich ever again.
But is it worth it? I don't think so, but that's just my personal opinion. Some people have lost entire tanks full of livestock due to this parasite, and they do not want to go through that again, and that's completely understandable. I have never dealt with ich so severe that it killed more than the one sick fish (and I've only lost one fish to ich, ever, and it was a powder brown tang). So to me, with all the fish I've kept, it isn't worth it. But like you said, treating for and preventing ich doesn't mean you can slack off when it comes to water quality, overstocking, aggressiveness, etc. If you keep your fish happy and healthy, they will live ich free. To me, that's easier to do than treating every fish. But, that takes work and you can't get lazy about it. If you get lazy, something else besides ich will kill your fish.