Let's think about the upcoming Star Trek movie for a moment, and consider how it's going to treat the canon. For me, canonicity is a matter of respect.
This upcoming Star Trek movie is J.J. Abrams's movie, but it's not his world -- he's just being allowed to play in it. So while we need to cut him some slack as someone with his own artistic vision and commercial requirements, I think it's also fair to expect him to show respect for the fans who've kept this franchise alive for nearly half a century.
And he can show that respect by not willfully ignoring aspects of the Star Trek universe that no one questions, such as the look of the NCC-1701 Enterprise. Fidelity to canonical information like this isn't just some slavish adherence to meaningless rules -- it's a respectful acknowledgement to those who have given their time and energy before him to help build this universe, and whose contributions do not deserve to be casually ignored.
I can live with some minor changes. I did not like some of the changes that Peter Jackson and his two co-writers made to Tolkien's story -- the inflation of the roles of Arwen and Eowyn, for example, and the elimination of "The Scouring of the Shire" -- but I coped because I understand the artistic and commercial interests involved, and because the core of Tolkien's story and many of its details were respected.
Likewise, I will not be pleased if Abrams & Co. take too many liberties with established and undisputed details of the Star Trek universe. There's no need to change those things even to stamp his own "vision" on the franchise. But if there are some changes made that clearly serve specific artistic or commercial needs -- they are required to tell and sell the story -- then I can probably cope.
As long as Abrams shows respect for the fans by respecting the canonical knowledge (which encompasses not just what the Enterprise looks like but the characters and the stories as well), I think Star Trek XI will do OK. Some fans will complain no matter what, but most are smart enough to know when real respect is being paid to their concerns.
Needlessly change too many things, though, and even the casual Star Trek fans will (rightly) feel abused. And then this movie will have a problem.
And -- my larger point -- that goes for a Star Trek MMORPG, too.