no towel- If I did carry one I would not want a metal eye-hook on it. no metal.
Whats the difference? The metal eye is only the size of a penny.
To the OP ....I keep one in the case. Why not have both?
Better yet....sell the one which hooks on the outside and if someone doesn't want to do that they can keep it in their case.... problem solved!
I just don't see the dilemma here with the exception of wanting a type of cloth thats not normally found.