Also, who writes a plot that has Earth facing the threat of destruction in the prequel when we all know Earth is around later?? With that alone, you kill suspense, and run the risk of driving viewers away.
Much like the last movie, the Xindi arc made a big deal that the timeline had gone horribly wrong and all bets for the future were off. I thought it worked really well, even if they obviously never would have destroyed Earth.
And then, of course, season four decided that those changes to the timeline led to
the Treks we know, not away from them.