Some of us spent quite some time to customise out characters' looks to not be lookalikes, yet way too many pearl shop costumes also set a fixed hairstyle. Please let us disable that.

You can just hide the helmet. There might be outfits I'm unaware of that force hairstyle changes, maybe? Outfits I have, if they have a different haircut it's always as a "helmet", which you can simply hide to show your character's regular haircut instead.

That works as a bandaid at best, as that not only hides the altered hairstyle, but also the helmet which I might actually like. Take the latest Nova costume for example. That tiara/crown looks nice, the hairbush it gives you looks hideous.

Yeah or they could stop adding unique hairstyles to outfits, and add more hairstyles to the character editor as asked by the players...

I hate having to choose between genuinely cool helmets and my own characters' hairstyles - I get it for some thematic helmets (like male Kibelius), but most aren't. My long-haired boys keep getting their mane hidden in destructive dimensional rifts, and my short-haired girls inexplicably grow mysterious locks (and they look especially bad with curly hair - not like it's great by default, with no volume added, but even more so when everything gets squashed together).

I know it would be hard for some helmets to fit in default hairstyles, but you could always give more versions of the same helmet where one comes with a hairstyle, one doesn't, and it becomes the player's business if they want to try making it look good on what they're already working on.