What's up with the visors?

So I finally unlocked just about every visor thats out there, and I still don’t know why there’s 60 different visors to unlock! Heck it seems like there are 3 different visors with the exact same shade of blue or whatever. And what makes the legendary visors “better” than the lower level visors when they’re the same color anyway?? Like “oh my spartan is so much cooler because he’s wearing the Rex blue visor instead of the recruit blue visor” etc etc

Simplest explanation is that it’s an easy way to pad out requisitions with minimal over head from the art team.