Is this actually an unpopular opinion? For sure horrible like all things in war, but I understand that the alternative was an invasion with a hell of a lot more casualties.
Yes. Unlike ground war, two entire metro full of people were killed and countless more suffered long term damages. Whatever the strategic value, this isn't a decision that I find ethical in any way.
The imminent threat of an invasion (assembled in staging area and ready to go) could have been tried before. It would have been very costly, but would have been necessary anyway for an actual invasion if the nuclear bombs didn't cause a surrender (there was a coup attempt to prevent it, so it was never a sure thing even with the bombs).