But not having the helmets doesn't mess them up!
They do a ton of fighting in Clone Wars without their helmets on! Lots of getting ambushed with helmets off and blasting their way out.
Heck, here's an extended engagement situation where Rex and Cody both have the opportunity to don helmets and elect not to despite repeated violence.Individuality is
hugely important to clones, even if it's expressed in small ways. Those high-maintenance haircuts and tattoos are an important expression of who they are.
The battlefields in the game have no context and make no sense anyways. There are multiple units who make no sense being on a battlefield at all in the first place, like Hermit Yoda and Imperial Probe Droid. Clones in a fight without their helmets is not only not a misrepresentation of the character, it's a common occurrence. Insisting that it's misrepresentation of the character is just petulant.