Part of my objection is that I wouldn't want to spend 3 days of my European vacation stuffed into a big festival. I'd rather spend 3 different nights catching good shows with some great stuff in between. Besides, I've kind of been there/done that with these sorts of things. No longer my bag.
However, I've been checking some of them out to see who's there and it looks like Maiden, Priest, Ozzy, GnR, and A7X are your main acts. This means plenty of them, and others, will be doing shows around there in June, on top of the festivals. Makes arranging a vacation easier when you get the added flexibility of more interesting shows. I suspect Saxon will be playing around Europe come festival season, and seeing them over there would make me very happy. APC and Megadeth are also hitting the festivals.