The thing is, until everyone agrees that they are safe to use, you risk looking like you don't care about other players' safety and that you are only concerned with gaining an advantage.
I've used these things myself, and I know they are safe, but others have not and may take a little more convincing.
The lense thing is true, ANY bb; whether it be Styrene, BIO, Graphite Coated, Silica or Aluminium will scuff or otherwise make a mark on a goggle at 400fps up close, so it's a moot point. We know the rated goggles can take it, it's a good piece of information to have "just in case" someone gets shot from within obvious mercy range.
Like I said before, everyone needs to understand the results and draw their own conclusions, not go on paranoia. Even if you still don't feel comfortable with their use, at least you made an informed decision and not one based on hearsay and conjecture.