That's why the dollar coin was redesigned in 2000. The old dollar coin had a reeded edge that was too similar to a quarter, so it was sometimes hard to distinguish if you had vision issues (or if you didn't have vision issues because they were about the same size as a quarter). The new ones have a smooth edge so you can tell them apart from quarters without having to look at them

True, and the new design is better than the old because of it. But it hasn't resolved the issue enough to really matter. Some less subtle physical difference is required -- put a hole in it, make it an obviously unique size, whatever.

At least that's how it seems to me. It's an interesting design issue. I don't personally care too much -- I'm fine with the paper bill -- but I do have curiosity about why the coin designers have made the decisions they did about the $1 coin.