Statistically, it's been fairly well understood for a while now that the benefits of a larger number of people cycling outweigh the safety risk of some of those people not wearing a helmet.

Infrastructure and keeping people separate from cars is more important, but mandatory helmet laws are a net detriment to public health.

There's entire swathes of people who just can't really have their hair messed up or it would affect them professionally. In Europe people tend to not wear helmets and it's not like it's a daily massacre in the streets.

There are different types of cycling. I would always wear a helmet to work because I live 6km away and it's a decent ride. There are hills and I often get to a reasonable speed.

Compare that to someone living in South Brisbane commuting to the CBD, or someone going for a leisurely bike stroll on the riverwalk - they may not go fast at all. We don't wear helmets whilst walking or jogging, but why is it mandatory for a slow ride?

The big reason helmets can be offputting is because they can mess up your hair. If the city wants to encourage people who live relatively close to their jobs to ride in, more flexibility on helmets could be a good thing.

FWIW I do think helmet safety should always be encouraged. Riding down a hill? Going more than a leisurely stroll? Wear a helmet. Makes sense. But it's really not that necessary for people who are riding slow.