There are users who want (or need) a curated, trustworthy experience. For them, an app store that heavily reviews all apps allowed on there and puts lots of restrictions on what they are allowed to do is ideal. There are also users who want to take the responsibility on themselves. They want the ability to host their own apps for free (or lower costs), faster update cycles, and just overall freedom. Those people don't want a highly curated app store (or rather, they want a co-existing alternative to the highly curated app store).
Perhaps the ideal situation would be that device comes with one default app store. That app store is highly curated and selective but it also allows other app stores on it. Those app stores can be reviewed in terms of their own quality but not on the quality of the apps they allow installing. The default app store can have huge warnings that these other store-like apps are not like the other apps and should be used carefully.