The one thing Classic Who has over New Who isn't alien cultures, it's costumes.
I'm always struck by how shows from the 60s and 70s, which operated on shoestring budgets, seem to have "higher production values" then their modern contemporaries due to the shows ruthlessly pillaging their respective studio's wardrobe. I mean, the original Star Trek based entire episodes around whatever spare set happened to be constructed on the lot.
New Who has no problem with historical costumes for the episodes that take place in Earth's past, but when it comes to the future...you'd think they could spare a little bit of the budget to come up with some suitably futuristic clothing (Even if it did involve multicolored jumpsuits) for the far future.
As for being Earth-centric, I sorta feel it makes sense, Post-Time War. We're talking about a man who's lost his entire race. The only place he has left is the world he's made "his project" over the years. It's understandable if he can't go back to Gallifrey, he'd spend more time on his "adopted" world.
EDIT: Also, it's worth pointing out a lot of the "alien worlds" Classic Who visits seem to be versions of the English Countryside...