Roboto was definitely an upgrade from Droid Sans. They created a sharp typeface with a more modern feel.
As far as Matias is concerned, it seems like a lot of his answers to decisions made are mostly fluff.
Simply put, Droid Sans (because of the way it was built) was made for smaller physical devices sizes (better readability), and now that displays are being created with more and more pixels, they can create something that feels a bit softer, and more progressive.
I know that most of you think that the articles are BS, and I assure you that most of them probably are, but implementing Roboto was indeed a good decision. Things move forward with technology, even typefaces ;)