Google's top designer Doug Bowman quit the company to join Twitter. Mostly, Doug didn't like how much Google depends on data to make design decisions.
His basic complaint: "When a company is filled with engineers, it turns to engineering to solve problems. Reduce each decision to a simple logic problem. Remove all subjectivity and just look at the data. Data in your favor? Ok, launch it. Data shows negative effects? Back to the drawing board. And that data eventually becomes a crutch for every decision, paralyzing the company and preventing it from making any daring design decisions." This is a portion of his blog post, find it at stop design.