Star Trek needed that to be said since there was a low point. Star Wars never had a low point, it doesn't need to be said. It was already made for a lot of people.
Of course, there might need to be some statements regarding the prequels.
It was said because Star Trek fans exhibit an unusual level of entitlement, and Abrams was demonstrating he had no obligation to pander to them. It was a political thing to say.
Actually, I think even that's overstating it. The way I see it, he wasn't try to distance himself from us at all. He was just working hard to convince the rest of the world that, no, really, this new movie isn't just
for hardcore Trekkies. Nor should it have been.
Which, yes, was a message that really
needed to be communicated to the general public at that point.
Of course, I also think that "This is not your father's STAR TREK" was an absolutely brilliant bit of marketing, and yet some folks around were annoyed by that too--even though that tagline was clearly aimed at the general audience and not us.
Again, the movie is what matters in the end, not the marketing, and not whether our fannish egos were flattered or bruised.
It's nothing personal.