I think it's the fact that people are seeing scratches and are concerned if it was the coating or the screen itself. I think if it scratches easily, it probably isn't a good idea. Finger prints can be wiped off in a second, scratches can't. But that's just my view on it.
plus it isnt even working really .. instead of fingerprints you get smudges all over the screen that look like shadows if that makes sense so i have to wipe the watch anyhow. same problem with the anti glare coating on the latest iPad. I actually HATE it