well, ckessel makes a good point of there being two different pricing models. Hence my statement about there not being consistent pricing across the board. This isn't simply someone wanting to pick parts of a package and expecting a lower cost. It's not as if someone's saying "I just want the NAV part of the tech package and don't want to pay for Xenon headlamps!". Tough, because the pieces of the tech package aren't offered a la carte. But the wheels are priced as individual upgrades for the base car, and the upgrade price is clearly shared for each option. But when you want the performance edition of the car, you're forced into paying the same price regardless of which wheels you choose. It'd be one thing if the only way to get the 21" wheels were as a part of the Performance package, and if that were the only option. Then you could see people swapping since you wouldn't even have that option to choose your wheels.
And yes, I'm sure you'd feel slightly different if you had your heart set on the 19" wheels but wanted the performance edition. I doubt I'll get the Perf edition, but I can certainly sympathize with those that want the 19" wheels.