Why Not Weeds Instead of Grass?

I just came in from mowing my weeds. My grass is probably a few weeks off from being ready to mow yet. Which brings me to my point. Why haven't we adapted weeds for our yards instead of sticking with grass? You wouldn't have to spray paint your yard green anymore, and they come back earlier from winter. There are lots of weeds to choose from, and several would actually make very fine turf by growing along the ground instead of taller. On top of that, certain weeds are able to edge out all other forms of vegetation. So after your weed of choice takes over you wouldn't have to worry about the other nasty looking weeds coming back?

Its not a perfect idea, and some people are more allergic to certain types of weeds than they are cut grass. But I'm allergic to it all, so why not go for something that would make a nicer yard and possibly require mowing less often due to the growing pattern. This isn't something I plan on doing. Like I said, several of the best weeds tend to take over, and I don't know if my neighbors would want the same weed yard that I envision as a possible alternative to grass.

I know a lot of people further north than Oklahoma have different types of grass that are softer to walk on and look better in the yard than we have. Most yards here are of Bermuda grass. Which does a nice job of spreading, but isn't all that soft or nice to walk on. It also isn't real quick to come back after winter. So the move to weeds might only be a good solution in certain locations, but its something I've often thought about here in my dry state.