I was flying with a former RAF fast jet pilot. He always wore his bone dome and suggested I get one myself.
No disrespect to the RAF man but their place of business can involve being shot at with all the unpleasantness that might then ensue. IMO flying an enclosed light aircraft is a different kettle of fish so I choose not to encumber myself with a bone dome, nor an olive drab nomex flight suit replete with squadron badges nor fireproof gloves.
Open cockpit I might reconsider the helmet but then it would probably be leather not kevlar.