It doesn't have to be flat or skeuomorphic. It 'just' has to be appropriate. ._.

“We made a conscious decision to embrace modern typographic design and avoid the excesses of skeuomorphism. But like skeuomorphism, flat design also has excesses.”

Thus was born what might be called (with apologies to Duarte, who never used this term) “quasi-flat design,” which is now fairly well entrenched across all of Google’s products.

“Tactile cues are important in touch interfaces, giving users a sense of what they can expect that’s touchable, and how it’s going to behave,” he continued. “It’s not just good from a familiarity perspective; It also touches the fundamental reptile parts of our brain, which knows that is a thing and it has identity and mass and lives in relationship to other things.”

From a brilliant interview with Matias Duarte, Head of design at Android, by Christopher Mims.