Honestly, we are long overdue for an in-depth look at Earth of the future in Star Trek. Yeah, Star Trek is about exploring space, meeting aliens, boldly going and all that jazz, but in nearly 50 years the most in-depth look at contemporary Earth we've gotten in on-screen Trek is the Homefront/Paradise Lost two-parter on DS9. And the only thing that makes that in-depth is seeing a restaurant in New Orleans. Earth is the most important planet in Trek. Humanity's homeworld, the capital of the Federation, and yet we know next to nothing about what it's like in the 23rd and 24th centuries.
I sure don't mind if a good deal of STID is Earth based. One Earth-focused movie in a 46 year-old space franchise isn't going to hurt at all.