Ok, so according to Wikipedia, "Googles' ADT was the official IDE for Android until 2015 but was replaced by Eclipse's Andmore and the official Android Studio."
So I was slightly incorrect in that there seems to have been a name change at the same time (as I say, I'm not an Android dev, so I didn't know that).
I was definitely seeing IntelliJ in use, and hearing a lot of praise for it circa 2011 - 2013, so it does look to me like the love for it precedes the Android dev environment switch.