Cosplayers aren't looking for "social acceptance" when dressed up. No one should be going to work, school, or the grocery store dressed as Sailor Moon or Bleach characters. Cosplayers go to conventions, photoshoots, and to hang out with other people who like anime and cosplay. (Like store events that have costume contests)
It'd be cool if America was as good as Japan at Cosplaying. There are great cosplayers in the US. We've got many great cosplayers who have great construction skills.
But we've also got the worst cosplayers that I could ever see here as well. People who's faces, body-types, or costumes just didn't match the character. There's not as much stigma here about not being 100% accurate.
Imagine if they turned you away for not looking the part? Most Japanese cosplayers would rather not attempt a cosplay than look bad in it. Plus they match the characters facial features since they are closer to resembling the anime style.
Plus they're cultured to be thinner (its not 100% though) and makeup can work wonders for any problems with faces. Combined with shops that sell cosplay items directly, and you get tons of fans with correct makeup, correct body type, and correct costumes due to living in a place that is more friendly and accommodating to cosplayers.
What the US needs, overall, to become a great cosplaying nation:
1. Easy access to tips on how to do makeup for characters.
2. More emphasis on correct body type for cosplay
3. Easy access to accurate cosplaying costumes so that everything doesn't have to be hand made or ordered from china.
4. Lack of interest in perfection in cosplay. Cosplay is only a minor part of US anime conventions. You don't go to a convention merely to dress up, so there are lots of other interests that get in the way of focusing on that perfect outfit.