Look at Enterprise, while the show wasn't all that bad, they had somewhat of a difficult time making a prequal show that had four shows and ten movies of onscreen canon and the canon was broken easily with this show because some of the elements of TOS were either forgotten, or chose to ignore, or just found it difficult to make it work because of all the onscreen history Star Trek had.
No-no-no-no-no-no-no-no-NO! (ahhh... taking a deep breath...)
Seriously, the problems that they had were UNRELATED to the history. It's easy to avoid contradicting "history." SIMPLY DON'T TELL NEW STORIES ABOUT THINGS YOU DON'T WANT TO CONTRADICT. Easy!
The real problem wasn't that they were bound by all the "history." The real problem was that they CHOSE TO STICK TOO CLOSELY to that "history" instead of trying to tell new stories.
The most maligned bits on Enterprise had to do with "Vulcan Mind Melding as an analogy for gay sex" or the inclusion of the Borg or the Ferengi or so forth. The choice to renovate the Akira model rather than do a truly different design. The choice to use the same damned technology as every TNG-era show has had, but to try to fake out the audience by giving it new names ("phase pistols?" "polarized hull plating?" sheesh!) instead of showing something more TOS-ish. And the overt efforts to make it a TNG prequel rather than a TOS prequel (until the 4th season when Coto was in charge, when he TRIED to fix it, though with what's widely considered to be with mixed results)
It wasn't the "history" that caused the problems. It was the LACK OF CREATIVITY on the part of the production staff. Give the same general show concept to someone else... someone who hadn't become psychologically submerged in their own personal version of Trek for the past couple of decades... but instead someone who hadn't had a chance to play in that particular sandbox yet... and "Enterprise" might have been a lot better than it was, and a lot more POPULAR than it was.
The Star Wars prequals. I saw all three in the theatre, (not a fan of Star Wars but gave them a shot), I thought they were ok, but I remember a lot of fans complaining about them because of either to much CGI of some characters or characters like Jar Jar Binks being introduced.
The complaints, really, were about the fact that the films tended to be more focused on imagery and less on real, identifiable people. The first movies were really about a group of people who were people we'd generally want to hang out with if we knew them in real life, and who we could imagine BEING. But the SW prequels were all about CGI to the exclusion of likeable people. Ewan McGregor was the one significant acting highlight of the prequels... if it hadn't been for him, the whole thing would've been a disaster, IMHO.
The problems with the SW prequels weren't related to 'em being prequels, they were related to them being POORLY TOLD and, more significantly, POORLY ACTED, overall. That said, they're still "good" movies... just not on the same par as the originals.
These were the main prequals I was speaking of (I never really saw any others, except Smallville).
Now Smallville worked I think because it didn't have all the "onscreen canon" as Star Trek does, so not much was complained about as far as I can recall. And I'm sure other prequals worked, like Batman Begins, but I haven't seen a lot of them so I'm sorry if I offended anyone. I should of been more clear.
Oh, GOOD LORD... I know you qualified that with "onscreen canon" but c'mon... the sheer volume of "canon" associated with Superman is orders of magnitude more than anything ever envisioned relating to Trek... and that's including every book, every magazine, every fan-fiction story, every damned "slash story"... EVERYTHING... ever told about Star Trek. Superman, or Batman for that matter, make Star Trek's "canon history" look like a speck by comparison.
And just so ya know... the "canon" arguments you'll hear about Trek are likewise dwarfed by the canon arguments you'll hear leveled at "Smallville," both in the level of nastiness and in the frequency of complaint.
