Marcos Tanaka pointed out this session from WWDC this year.
Jiabao Li of Apple’s prototyping team:
So, we have our ten main features, and we know people love clean interfaces. So, we’ll just throw all the non-essential features into a menu. Clean and easy, right? You may have seen this icon before. It’s called a hamburger menu. When we tested our interface in the hands of people and found out that, when the hamburger menu is closed, people don’t know what’s inside. The three lines don’t convey anything about the features inside. So, instead, we decided to go with a tab bar navigation system, which appears at the bottom of an app and lets people quickly switch between different sections. It’s better because you can immediately see the most important features of the app.
The most minimal user interfaces might not be usable or simple because people won’t know what to do. Because when we hide things to make the app look minimal, we increase the risk that people won’t find features. They might even forget that your favorite feature exists.
Inconsistencies at big companies are to be expected. But it is fairly shocking to see, in a WWDC session, such a blatant dismissal of the visual interface trends creeping throughout Apple’s operating systems and applications. The teams that work on Safari, Music, and Notification Centre should talk to Jiabao when they get the chance.