My point is that, regardless of their cut, the "exposure" the App Store supposedly brings is likely practically nil, unless you're lucky enough to get 'featured' by them. So it's not like you end up being able to save costs by getting rid of your marketing department because "hey, you're on the App Store!".
Additionally, you're not allowed to sell the same software at a different, higher, cost to make up for Apple's cut, so you effectively and up losing even more revenue, since you need to keep your own existing marketings costs, maybe even have to pay into Apple's ads on top of your 30% to market there as well for actual exposure, since you essentially end up as a needle in a haystack, because the App Store is full of cheap crappy apps that Apple is pushing developers to create to fill up their store, because "courage". (edit: I read from other comments that differing costs seem to be allowed now - "Hallelujah, it's a fucking miracle!")
Additionally you don't have any option of providing the download yourself-they force you to use their "service", and hence "pay" for said service, instead of being able to control that cost yourself. Because "courage".
And besides, I don't see how comparing fee structures between completely different industries as justification for Apple's cut is a valid argument in this case ("they do it too" or "they're even more" means the other guys are just as bad or worse - it's shouldn't be a pissing match of "who's worse?").