I disagree. I do not think this is a major consideration for most users. The idea of multiple software stores, some of which may or may not be trustworthy, is not high on the list when comparing phones.
Issues they do care about in general order of importance:
* Cost of the phone
* Provider support (e.g., will I be able to use this phone with my carrier)
* Features of the phone (does it have a keyboard, or a camera, and what does it look like)
* App support (can I download apps I am interested in?)
The fact is, most people have a rudimentary understanding of how the apps work and what risks they are taking when they download software from the internet. Nor are they aware of how powerful and versatile these pocket-computers really are. So long as they get their email, facebook, music, mapping, a few choice games, and perhaps the usual word-processing apps, most people are satisfied with the selection they get from the app store (there may be more to that list, but for the vast bulk of people, everything they need or want can be had from the official app stores). It doesn't occur to them that they are "locked-in" because they already get everything they need so they don't go looking for more. However, when they do feel the restrictions - when they discover that FlappyBirds or whatever fad-app isn't available on the app store, they are more than willing to visit alternative sites to get their software fix, regardless of the risk this to which this puts their data.
In other words, it is true that users usually do not care about being locked in to one application provider. But they also don't care that the official app-stores vet the software either and when push comes to shove they will readily accept software from any source. Once made aware of the issue, the multiple sources of apps is a selling point for Android, because it gives the users more selection. That it comes with significant risk to their privacy and data is rarely a consideration. When the garden wall gets in their way, they dislike it as much as power users without understanding the benefits it might bring.