Not challenging your claim that East-on-top is common (since I have no idea), but: it's called the orient because oriens is Latin for rising, and the sun rises in the east. Many other languages also have a word for east based on their word for rising. For a cursory reading, check out the Wiki article on the etymology Orient: https://en.wikipedia.org/wiki/Orient#Etymology
The grandparent comment makes a valid point, just backwards. The reason orientation and orienteering contain the string "orient" is because Europeans historically put the East at the top of maps, a practice which changed some time after the introduction of the compass.
Which points North, unless it points South; Chinese maps traditionally put the South at the top.
I learned more than I expected about maps. So so you think it was a style decision in the late 1800's to make a map with the top facing east? Or was it still common?
North was pretty standard by the 1800s, or indeed by the 1600s.
But there's a map in the public library of my hometown, showing it in 1890, in which the Old West Side is at the top of the map. So I'd guess that non-standard orientations were more common than they are now.