I think because of see no evil 2, he's working unmasked for good
See No Evil and it's hell spawn can die in a fire.
The mask was getting a little boring. I mean everyone knows what he looks like. He brought it back because he hated what he had become but that's long over
Shaving off half his head and his eyebrows is what's boring.
When Kane unmasked in 03, I was legit scared of him, so that incarnation will always be a personal favorite of mine.