Humanity being special has always been part of Mass Effect.
Maybe, but is humanity the most interesting part of Mass Effect? I don't think so. Humanity doesn't make Mass Effect unique, it's universe does. There are already so many science fiction stories that are focused on humans and the planet Earth, but how other science fiction franchises have the Asari, Krogen, Turian or other races that Mass Effect has? I would sooner ditch Earth in a heart beat and fight for them than taking back what so many other science fiction stories have done in the past.
I completely agree. I'm tired of the "humans are special" and "Earth is the most important planet of them all" tropes in sci-fi. While ME1 obviously made a big deal about humanity rising to such prominence in such a short amount of time (unbelievably in less than thirty years, in fact, but that's an entirely different subject), other than that it did a good job of making humans seem like just another species out of many in the galaxy. Earth wasn't important (other than Anderson's "Even Earth is at risk!" line during his tirade about Saren) and the Citadel was the heart of galactic civilization.
But ME3 took the focus on Earth to absurd levels. It got to the point where every Shepard kept blathering on and on about Earth no matter what their own life experiences were. Most of my Shepards were either Colonists or Spacers, they weren't born on Earth and they didn't grow up there. But in ME3 they keep talking about it like it's their home, like it means more to them than the places they actually came from. Sure, it's the cradle of humanity and the vast majority of the human population still lives there, but it's still just one world out of many, and not even the most important one.