As was said earlier, the fact that US operators don't insist on this may be due to the potential for legal action were someone to get injured. Although in most cases it seems to be local authority rules, rather than the dive operators themselves.
Last time I was in Cozumel, where the Marine Park guys can be pretty strict on the no gloves policy (also no knives, as I recall), the dive boat was very quick to point out that it did not apply when diving the wreck. Can't remember the name of it, but it is a good dive, the Oxycontin or something like that. Anyway, they recognise that you may need to be able to push, hold, grab the wreck in certain parts to make your way through it and as an artifical reef, the no-gloves rules didn't apply. Just thought I'd add that to the discussion.