> If by "higher quality apps" you mean loads and loads of thinly disguised ad- and spyware, as well as generally useless crap, then yes, curated native app stores are "great".
> I'd say the density of pure and utter crapware has never been higher than in the various app stores.
Compared to what? Download.com? Tucows? Every app put on the internet, ever? There are lots of useless and borderline malicious apps on the existing mobile app stores (and a handful of downright malicious apps), but I'm far from convinced that it's in any way worse than what we've had so far on the desktop. All the "browser toolbar" apps out there, by themselves, are enough to make app stores look good.
And having a unified place where you know you can get the official version of any app, along with any updates, and from where you can painlessly re-install all your apps when you get a new machine, cannot possibly be a bad thing.
What do developers get for that 30% cut? In Apple's case, they get access to a huge userbase who has already entered their credit card into the system and just need to press "buy"; they get access to payment processing, currency conversion, and storefront internationalization, close to world-wide, without lifting a finger. Is 30% "fair"? Probably not - it's probably a bit high for small developers, and larger developers may prefer to opt out and solve all those challenges for themselves, for much cheaper. (edit: for desktop Mac apps, they can. The fact that some developers choose to sell their Mac apps through the App Store suggests the 30% is worth it for those developers. It's important that those developers still have the choice to sell their desktop apps through other channels - so far, anyway).
Yes, it's ultimately about control, and about that 30% commission. I did say it's less choice, not more. But you can't say there are no benefits at all, to both users or developers.