Why don't you clarify your argument for me. I don't want to assume anything, so clarification would be helpful.
It seems like you're saying 'if it performs worse, then it's cosmetic.' Is that the basis of your argument?
Whether or not someone leaves the pistol grip on for cosmetic reasons has no bearing on whether or not it's actually cosmetic.Pistol grip use is subjective, and leaving one on because of how it looks after finding it performs worse makes it cosmetic.