My only problem with retconning everything post-OMD is that it chooses any new fans that came in with BND/Slott to have to "choose" between that and the marriage. And that's likely to lead to some more marriage anymosity and attempts of pulling an OMD in the future. I get that BND lost more fans than it gained, but it's not like the anti-marriage crowd was ever a majority in the first place, and they still managed to get their agenda through.
Of course, sometimes you have to retcon things. The Zeb Wells stuff has to be officially retconned. The BND/Slott run though is more superfluous than "so damaging it needs to disappear".