Like many other features, it was the right decision at the time.
And MOBI7 and earlier contains features designed to make it compatible with early versions of IE. Fortunately the world has moved on, even MOBI (thank god) has moved on. What remains stuck in place like a slowly melting glacier is PG. The notion that you can do a book once and that book remains frozen in time for the rest of eternity is simply wrong. We need a way to fix, maintain, and move books forward which is not dependent on the WW'ers to do the heavy lifting. The idea that PG and the PG community is not allowed to touch a book after it has been submitted because doing so might offend the vanity of the submitter (including DP) is simply a wrong-headed idea. These books do not belong to DP, they do not belong to the submitter, they do not belong to PG, and they do not belong to the original author. These books belong to the public, and PG [when its got its head screwed on] is simply acting as a facilitator to get books to the public which the public already owns. Having books with screwed up formatting which cannot be enjoyably read on ebook devices is simply lose/lose. We need a way to fix broken books. Right now we do not have a way to fix broken books. That is stupid, and it is pathetic.
People who want page numbers in scholarly editions are hardly unrealistic.
Page numbers could be set up to "work" where "work" probably means that they have to magically disappear in MOBI versions at least. I doubt EPUB readers want them either. The technology to hide page numbers is built into the ebook readers, it's just that PG isn't implementing it right, nor are the DP formatters implementing it right. But the problem isn't page numbers in scholarly editions. It's that page numbers are being implemented incorrectly in every "See Dick Run" book and then ebook reader customers see this hash of random numbers showing up in the middle of paragraphs. And/or the already limited display space of an ebook reader is needlessly being thrown away for a "feature" which doesn't even work.