These are outlawed for closet use because of fires.
Closet Lights – New Rules for Closet Lights
"Surface-mounted or recessed fixtures are both permitted, but exposed (uncovered) light bulbs are not. "
Has anyone ever had a hot bulb get wet? I have and they shatter before the element sparks/burns out. All it would take is one drop of condensation and some combustible bilge fumes.