Tolerance gets less important as you move into the consumer market - surface finish is far more important.
Sure, snap-fits need to be pretty tight to work well, but do you really think people will care if their earrings are 0.05" out of round?
The main issue now is really materials and processing cost - it's expensive to get the materials because they're engineered to work with a machine, and there are still things like finish quality, color, etc. that need to improve, but there are tons are good products that can get around these constraints.
Sure, snap-fits need to be pretty tight to work well, but do you really think people will care if their earrings are 0.05" out of round?
The main issue now is really materials and processing cost - it's expensive to get the materials because they're engineered to work with a machine, and there are still things like finish quality, color, etc. that need to improve, but there are tons are good products that can get around these constraints.