I'm not sure I agree with your earlier comment about saying you might as well buy a GTD if you don't spec the performance pack Exonian! What kind of logic is that?! I don't want a petrol vs diesel debate, but I just prefer the smoothness of petrol engines, and I prefer the looks of the GTI over the GTD in terms of wheels, red accents, and interior. There is more to a car than just performance, and £1000 extra for just 8 seconds gain around the Nurb simply isn't worth it for every day use in my view.
Yep, it's an expensive option on an already reasonably expensive car. Most people in the market for a GTI are not after a car that that they want to drive like they are on a track. Of those who do go for the performance pack, I suspect very few will actually be able to truly appreciate the difference, but just go for it for pub talk. Personally, I've never had an issue with the brakes on my MkV GTI, even fully-loaded, but then again, in such a state I wouldn't drive it like I'm around Brands Hatch!