Typically anything that is mounted to the outside on the ROV is a potential snag point that can get stuck into ropes or fishnets. There is also general little or nothing to protect such equipment against impact, scratches and dents.
The typically 4 light setup is an example of this where the two upper lights sits externally on the frame.
I have integrated the lights into the buoyancy to keep them out of harms way and also to prevent them from snagging and potentially trapping the ROV outside rescue reach for a diver.
Please have look at the pictures to get an idea.
Note all buoyancy is still in use but has been cut and moved slightly out of the way of the lights.