[Burt]

I think people get to caught up in continuity and sometimes miss the point. Yeah, it's nice to have, but doesn't mean it's always the most important thing.
Some fans always seem to want the history of TV show to be one easy simple story laid out in a nice straight line. But real history isn't really like that. It gets twisted, confused, copied, buried, and lost. So what the Xindi have never been talked about in other Trek episodes? Listen to people talking around your town. How many of them talk about the Napoleonic War's? I'm guessing very few.
And so what that new starships and different starship classes pop up? Can you name all the different ships in your countries Navy? I know a fair bit about the Royal Navy as I've studied it and even then, I mess up on some ships histories.
Personally I like that Trek's history is a bit more complicated. Makes it much more interesting!