I remember from the AGM many years ago that it was square so...

I remember from the AGM many years ago that it was square so they could address each pixel individually. The way it is set up, each pixel didn't have it's own individual connection to power, rather they are connected through the rows of pixels. They figured out a way to address each one individually, using this method. However, I would assume that a square is the cheapest way to manufacture and the most flexible as far as real world applications go. That's how I remember it anyways, happy to be corrected.