1) there were multiple app stores
2) Apple would curate their own app store
I think that approach would solve so many problems. The first would see app stores that were limited in scope (not all, but some). Some would curate, some would not. The non-curated ones would be easily avoidable.
The second option needs to happen. The shovelware on the Apple app store makes me want to avoid it as much as possible. If Apple would hyper-aggressively curate their own app store, I think the overall quality would rise.
Of course, I realize this probably won't happen. Lockdown of the app store is directly tied to their bottom line.
Android also has the issue that installing from a third party app store requires enabling installing off all apps from "unknown sources", which presents a malware risk. It would be nice if you could insert trusted third party app signing keys.
There is also the issue that device vendors are contractually obligated to not install any third party app stores if they want to have access to the Play store. Of course, I'm generally in favor of this, since 3rd party app stores are generally awful (and certainly people don't really want a carrier or device manufacturer based app store, which is what would happen). But, that restriction also keeps 3rd party app stores from getting any traction, which leads to developers ignoring them for the most part.
Personally, I'd hope Apple would keep only the five or ten best-of-breed apps in each category; the apps that best showcase Apple's tech and UI.
So, basically keep, e.g. 100 categories * 10 apps, like 1000 apps, kill the other 1499000 apps, and alienate millions of people and especially all those programmers...
So while it would be nice to have, I don't see anything special in having Apple curate the app store themselves.