Android smartphones will continue to dominate the lowest spec hardware, especially in developing markets like China. Because the Microsoft OS cost adds to the device bill-of-materials, and Android -being open source- does not have this cost.
By analogy, its very hard to see how Microsoft will produce low-spec tablets that are cheaper than what Amazon does with the Kindle Fire - and its successor products.
I spend about 2-3 hours a day on my iPad+LTE with Skype (Fewer dropped calls than trying to use my iPhone + AT&T, better quality sound) - so I appreciate the importance of Skype.
Could somebody who valued Skype on their tablet consider the Blackberry Playbook? Doing a quick google search suggests that isn't the case (as of Feb 2012).
I predict that apps are going to be increasingly part of some larger overall business plan and less something sold for direct profit. Big players like Facebook and Nike need native apps in the store but they also have deep enough pockets to fund ports to Android and WP. We're already seeing that Apple's dominance in the app market doesn't translate to dominance in phone sales and I think platform-specific apps are going to be even less decisive in the coming years.
The second, much larger category of people, consists of those who, as you said, probably won't be inconvenienced by that missing app - but they don't want to be seen making a bad decision. These are the people who either are afraid of having purchased the "wrong" (whatever that means) device, or are worried about missing out on future benefits from their platform when developers don't roll out the AAA titles for it.
There is a reason why App developers pick and chose their platform. There is a reason why, my poor friends with Blackberry Bold's are getting almost NO application support from developers. My mother complains a little about how her HTC Desire HD lags behind my iPhone on some features or capabilities of some apps, but, nine times out of ten these days, the cool new app that I'm using on my iPhone is not (and probably never will be) available for the Blackberry.
So, the average user is actually smart to avoid these "dead end" platforms. They realize that, while there may not be a killer app that they need right now, if they truly want to enjoy the "App Ecosystem" - they need to chose a device that will get great developer support.
And right now, that is IOS first, Android Second, and, if Microsoft has anything to say about it, WP7 third.
Blackberry and Symbian are basically dead as far as App Development goes, and, as their Applications die up on the vine, their users are flocking away.
Some users see this as an opportunity, because with no competition, they have a much easier time making themselves seen, and (for the limited audience that they have), have a better chance of making revenue.
But that's from the _DEVELOPERS_ perspective. From the _USERS_ perspective, they could care less whether the individual developer is able to make a lot of money - all they care about is whether the World Class Apps are available for their platform.
I guess this is a long way of me saying I disagree with your thesis that Applications aren't critical to the success of a platform. Without the App developers, the platform will die. Microsoft realizes this.
Microsoft's chicken & egg problem is that Apple owns the app-rich high end and Android owns the low-end so they have to find some way to squeeze in. I think they'll have at least some limited success just using their financial muscle to push their phones into shops.