I'd prefer the drivers keeping with one design over their driving career, maybe changing a colour to suit a new team or sponsor, but still keeping with their original overall design. Freddie Spencer's helmets styles
That's not to say I didn't mind the one off's for a special race, or career milestone, or like Button going pink after his father passed, when the drivers do that, it's out of the norm and the special paint job really stands out.
There are ways around this problem. Colour shifting paint, different colour depending on the angle of veiw.
Glow in the dark paint for pinstriping it would look off white all the time until it got dark out, Night races.
Thermochromic paint it changes colour with the change in temperature the drivers helmet would look one colour out on the track and then another colour when out of the car. there's also
Paramagnetic paint changes colour with the help of an electrical current running though it. I don't know if it would work on a carbon fiber helmet ?
Note: I don't know how real or fake the Youtube video's are, there is a paint that can do this. It's just I'v never seen it on a car before
Anyways there are some ways to get around this crazy rule