Dude, you're far too wedded to the canon you've built up as something immutable.
There's too much retcon in Trek to suggest that the canon might be immutable. But it's also valuable. The history not only provides back story automatically, but it also gives it gravitas for free if you just don't shit on it. Like, for example, the theme song to Enterprise. Ugh. That was some of the worst awfulness which was ever awful. I was constitutionally unable to watch that show if I had to sit through the intro music.
Because now they can focus on making (hopefully good) movies
They made exciting movies, but I don't want to watch them again, because they had no substance. They trotted out some characters we were supposed to care about, and then crapped on all the reasons we cared about them. If they were good movies, they wouldn't have needed to call them Star Trek. They weren't, so they needed Trek characters to bastardize.