It's not only a trend among average consumers though, it's also sadly a trend among us developers: not a lot of developers are willing to spend even a single dollar on software they have to use every day. "Do you have a free version?" "Why do I have to give away the application I spend years full time on writing? Do you work for free?"
I don't think this will end well. If we less and less value software on its true worth, it will become less and less attractive (or even possible) to write the software we need in a society which more and more relies on software. Watch this great presentation by Erik Meijer [1] where he addresses this problem (and others ;))
I think part of it is the trust proposition too. Why do people pay {BIG NAME DEVELOPMENT COMPANY} {>$1} for an app in the desktop world? Support and upgrades.
What are the two things that the app store has more or less excised from customer expectations w/ regards to a purchased app? Support and upgrades.
Best of breed (aka Panic) aside, obviously. But you have to admit there are a lot more fly-by-night app developers than on desktop.
Edit: It'd be interesting to see how "each feature costs $1" IAP would play out. (Odd parallels to the arguments cable companies are having re: a la carte pricing)
Pre-iPhone, a $20 shareware app was considered pretty cheap. Now less than 10 years later the highest quality apps from name brand companies can't command it.