I think in technology circles people just love to complain. They think it makes themselves look smart for some reason.

Personally I'm a fan of MD and other minimalist styles.

But it doesn't matter what technies think. What matters are the users. Google did extensive usability testing on MD but just to be sure we did our own testing because we weren't sure how it would go over in Asia and Google is less focused on the Asian markets. Turns out the users fucking love it. We're talking about a hugely positive response across the board: men, women, children, poor, rich, artists and police officers. Three most common comments: (1) clean like Apple! (2) it's cute, not too serious (c) it's simple, easy.

Yes this is subjective. It's not even clear how a design language can be "easy" but that's what the users feel. Given that kind of feedback and considering all the hardwork Goog has already done it'd be crazy not to leverage it.