I don't think that is necessarily true. I actually think it's quite the opposite - people wanted Star Wars in HD and the 2011 BD was (and is) the only way to get it, so they bought it. But that doesn't mean, that many of them wouldn't have preferred the unaltered version if it was available, I mean, most of us own the 2011 BDs, right?

So, if they just re-released the 2011 version, those people, who already bought the BDs would have no incentive to buy them again but if they released the OOT, a lot of people would buy the new release, even if they already own the 2011 one.