We buy iPhones because we are particular about our hardware; if you guys think OP is being so ridiculous, why don't you just use an Android phone that some store employee has spiked to you from across the room? That's a much more rugged and proletarian experience.
So you're basically enforcing the stereotype that Apple users care about style and pretty things over substance and functionality.
It's pretty silly to suggest that if one doesn't get their jollies unboxing and admiring their beautiful new iPhone then there's no reason to buy one. This is exactly why people call iPhone users iSheep, saying we'll buy anything as long as there's a pretty Apple logo on it.
I get where the OP is coming from and given the choice I'd prefer to open up my own purchase as well, but I also understand why for most consumers what this salesperson did would be considered outstanding customer service, not an offence.