The app launcher in the Google Bar makes it easy for users to quickly access Google apps like Drive, Gmail, and Calendar. Savvy users can even customize the launcher to place the apps they use most at the top and they apps they visit less often at the bottom.
We want to make the app launcher more convenient for new users and those who don’t take the time to customize it. To do this, we’re introducing a new default order for apps in the launcher, which will more prominently feature commonly used apps like Gmail, Drive, and Docs. This new order will appear on Tuesday, August 1st.
From what I can tell it looks like Google is putting the most used and popular apps in the default area to improve and encourage usage.