"But because of a historical accident, collapse postulates and single-world quantum mechanics are indeed on everyone's lips and in everyone's mind to be thought of"

I think there's more to it than historical accident. After all, it was a historical accident, of sorts, that people believed one could sail directly west from Europe to arrive in Asia, but once a continent was found in between it was no trouble at all to overturn that belief. Historical accident is not the only reason, or necessarily the major reason, that we are still struggling with single-world QM today. I think if we had started with Everett, and someone had later come up with Copenhagen, the latter would gain a nontrivial number of adherents. Note: this should not be taken as justifying Copenhagen in any way. I am merely saying that this particular analysis of the egregious error that is Copenhagen is not complete.