I would agree with something stipulating that the drivers helmets need to be clearly distinguishable (between team mates). I was at first race in Melb this year and took a long time to even realise Hamilton was on track, thought Rosberg was just doing a lot of laps! Spent a lot of time squinting at the TV through the season to decipher Verne/Riccardo too.
Another thing people don't discuss is the cost. Anyone like to guess how much Vettel's helmets cost over a season? In times when most teams can't function without cashed up drivers it sends a strange message that RB probably spend a lowly drivers salary worth of cash on painting 20 or 30 ridiculous helmets a season.
Despite what people here say I do think it's a small part of what's hurting the sport - nothing iconic or memorable about a drivers personality in the car anymore. The references to the 'old days' are good. When Senna's yellow helmet (clearly Senna, not Prost with his white and blue) or Mansell's Union Jack (not Piquet, because his was a bright red tear drop) came around the corner it was adrenaline pumping stuff just seeing the helmet! I think fans connected with that helmet like footbal fans connect with the colour of their teams strip.
So, mandate drivers helmets be distinguishable between team mates (colour scheme?), allow ONE 'special' helmet per season.
Make drivers stop all the crap and give the fans an identifiable hero.
Something needs to be done on how the public perceives F1 and this could be a small starter - get back to basics as well as cut some frivalous spending.