The visibility thing is a silly argument against NWUs. They aren't any worse than dungarees, utilities, or dark blue coveralls at being seen in the water.
I'll flip you one more. Give me a reason why they were good a color? Color me ignorant but why would you even need camouflage aboard a ship? The Corps designed a uniform to replace a 30 year old tri-color design that was obsolete. There was a need for new camoflage.