I think it is also a safety issue.

If a manufacturer removes a safer product and replaces it with a product that is less safe and if their advertisements and representatives have said it is just as good (Simms has made this claim) for wading as the former product, I think it opens Simms up to law suits. It can either say it was wrong and rubber is NOT as safe as felt OR it can offer felt. If Simms instead offers felt, it has a weak defense in that it is the angler's choice as to what they buy.

I wonder if the liability issue was considered. Orvis says that rubber is not as good as felt and Orvis does not even sell rubber soles WITHOUT studs.