Well it was interesting to see public opinion, and I'm not going to argue with your opinions.
However Seraph has made 3 plot errors, so i fell I should point them out.
1:Myrdred was on the Warlocks Good side because he was on Mjarin (their leaders) side.
2:SB did that ritual because he no longer qualified for HG immortality
3:Gower was not a full nation, it was reduced to small towns, of which Yürsgard was the only remaining town that was big enought to be classified as a town.
Finally on the matter of Myth III canon i'll take 2 viewpoints 1 legally, Legaly Take 2 decides what is canon thus Myth III is canon.
Artistically I'm going to take a few examples
1:Star Trek, does any of the episodes (series') made after Gene Rodenberry's death make those episodes any less Star Trek.
2.Star Wars the Empire strikes back was not totally written by Lucas, it mainly written by someone else.
3.The massive History of MiddleEarth books written by Christopher Tolkien, are the any less Lord of the Rings Canon.
Perhaps this is what Bunige intended all along (Okay thats really far fetched but hey) They had acces to bungie concept work, they may have changed it less than you think.
On Myth IV which would you prefer, a group of fans doing another version ala Mumbo Jumbo style, or a Microsoft controlled Bungie, where the game is released on the X-Box. on PC a year later and Mac 2 Years Later?
-zeph