If other boats cannot see you then you risk being hit by another boat. I'm not exactly sure of the rules/laws in the BVI for running a boat at night, but there is a reason in back in the states you are required to have your lights (configuration depending on boat size/type) on while boating at night.

Sure if you use a flashlight and look into it your night vision will be affected, but if you shine the light up or in front of you it won't matter that much. Then again with most of the dingy's coming back from bars I'd say most are more impaired from the drinks then a little flashlight and it's more important the others can see you.