Standardization.

So what is standard aabout using heavier wire than is called for? 15 amp
and 14 ga. is what is standard. 20 amp feeds are only required in a few
areas of a house. They are what is not standard.

Even in small quanties of 100 ft put ups, 14-2/W/ Ground is about $29
while 12-2/W/Ground is about $50 or a difference of $21/100 ft.

No self respecting contractor is going to buy wire in less than at least
2,000-3,000 ft at a time, so that price difference will drop.

Even if it doesn't, 3,000 ft of wire in a building only adds $63.

Price is only one part of the equation. Pulling the heavier wire and
working with it inside of boxes is a definite pain in the butt.

Go for it, if you want, but don't claim it is for standardization. Every
licensed electrician out there will argue with that.
--
Jim in NC