Is the "boys" bike helmet cheaper because they sell more of them, or do they sell more of them because they are cheaper?
How many girls are wearing a "boys" blue helmet because it was cheaper? Was cost the deciding factor, or was it the fact that almost all boys and most girls don't like pink?
Rather than force manufacturers to make what YOU want and price them the way YOU think they should be, why not start YOUR OWN bike helmet business? Order some plain helmets, design and apply the colors you like, and sell them at a price you think is fair.
THAT'S how it's supposed to work. Nobody, including businesses, are required to make ANYTHING a certain way as long as they comply with safety standards.
All this person is going to accomplish is reduce the number of manufacturers and choices available to the consumer.
Pink helmets cost too much? Fine. We're discontinuing the pink. Feel free to buy the cheaper blue one now.