Ah, right, forgot about overseas.
What's truly frustrating is how we can see from Xylon's screenshots that Paramount had unmolested versions of I, III and IV on their hands. Sure, they might not have been all-out restored like Khan, but they could've put them to blu-ray without any complaints from this enthusiast. Instead, for whatever reason, they decided to filter them and the results look terrible.
We don't have "before DNR" screencaps for V, but I'm guessing it was a similar situation: nice new transfer needlessly filtered to death.
Then there's VI. It's pretty clear that instead of going back to a film element of some sort, such as an IP, Paramount simply dug up a 1080i broadcast master of the theatrical version, filtered it and put it out on disc.
It's interesting to note that with TMP, III, IV and V, Paramount wouldn't necessarily need to spend a single penny to give us picture quality that's at least satisfactory. VI would need a proper remastering, though.
Here's what Paramount could do: Next year, coinciding with the new movie's release, quietly reissue all the movies with different cover art (or something) Gangs of New York style, maybe call them "ultimate editions" this time to make the re-release seem more justified. Like I said, the pre-DNR transfers of the theatrical cuts of I-V appear to at least be in good order so it would be a win-win situation.
Here's where they'd need to spend some money and put in some effort: re-render the TMP director's cut at full 1080p (if not higher), include the longer version of Khan via seamless branching, making sure the extra scenes are preserved at the same quality as the theatrical. Properly remaster VI and include both versions via seamless branching.