Weapon Skins Question

So I was thinking about it, and I was wondering why only very specific weapons (namely the UNSC ones) allow for customization still.

You can’t put an emblem, charm, or skin on about 2/3 of the sandbox, so what good is having that option in the game?

Maybe I’m overthinking it, but I feel like it’s just a way to limit the work related to selling skins in the store and battle passes. After all, they couldn’t leave the weapons out entirely in that regards, it would have lost a possible lucrative revenue stream.

But that being said, I sure would like to add some drip to my Heatwave or Shock Rifle.