Wouldn't it be easier and more beautiful if the screen was arranged bottom right to top left instead of top left to bottom right - the way my thumb moves, my most important input thingy?<p>Just order all icons that way and nudge app developers to put important buttons in thumb's reach - and not as far away as possible as it's being done almost always today.
Isn't that largely the point of the Material action menu, so you have a thing in the lower right corner (near the usual resting position of your thumb), that either does the new or add function, or spills out frequent actions used in that app?