Lets assume that wearing a helmet was no "safer" than wearing a hat. Would you still one for the "convenience" of it?
Goggles stay in place
can not be ripped off be low branches like hat which means that your goggles stay on as well
goggles do not fog when on forehead
ear are better covered
more rain/snow proof
goggles do not move your hat around
warmer/ cooler than a hat
I actually can think of a single way a Hat is more convenient than a Helmet. If the helmet was no safer(I do feel it is though) I would wear it anyways.