I wouldn't call it economical, just cheap likely.

Most tire fillers have a proper gauge on them anyways.

That's a good idea. You would be able to check your tire pressure at any time with a quick glance. Most people don't check their tires often enough simply because they are too lazy to get out a gauge and use it. This would help a lot. Instead of mounting it in the tire directly, it could be mounted in the rim. It might be possible to design one to mount in the valve-stem hole. That way, it would be possible to add them to any regular tire/wheel.

Just make it easier to read than the "piston" models currently in place, and keep them on the pumps. Putting one on every tire would require drastic changes in manufacturing, and would introduce a likely point of failure. And they'd always cost more than gaugeless tires.