Re: I guess so?
The key thing in these various litigations is not to say that Apple can't run an app store, or that it can't charge a commission. The argument is that only Apple can run an app store for iThings, so there's no alternative and no competition. No competition means Apple has been able to charge 30% and developers have had two choices - accept it or don't sell apps for iThings.
In a competitive market, the fees Apple charge would have to be a balance between making a profit and being competitive with the alternative app stores - if 30% is too much for the market, then you'll lose apps to the alternative stores.
Personally I try and avoid the "app for everyone and his dog" approach. For most stuff there's a perfectly acceptable, functional, cross platform option - it's called a web browser.
Leaving the iThings and "all your privacy belongs to Google" Android, on my laptop I'm not bound to use one company's app store - I'm free to go elsewhere (such as the developer's own site) for my software. As mentioned, for some developers it may make commercial sense to use (say) Apple's app store, but where it doesn't, they shouldn't be forced to.