Android is a hit with youth, and the less technical interface compared to the desktop is very welcome to older generations and those who are less technically saavy. Believe it or not, there are many people out there who still struggle with a mouse. Though ChromeOS supports touch, the apps they run generally are built around a mouse, whereas Android apps are ALWAYS built around touch.
Also note that the 6.0.1 update for Android introduced a slightly different tablet UI again.
Since 4.3-4.4, tablets have sported a bottom bar with 3 buttons centered. Now two of them (back and home) are found in the bottom left corner, while the "switcher" button has landed in the bottom right.
While this seem to be nice when holding a tablet with both hands, it also works well with "Fitts' law" as corners are easy to hit with a mouse.
