Only because the architecture is wrong!
We're back to needing lots of developers because every business wants to have a custom app and the skills to build them are still niche or at least not commoditized yet.
There's no reusability yet, and a lot of effort is being wasted reinventing the wheel. So, more developers are needed.
But, I predict that once people realize that the client/server approach of an app loaded on your phone is a problem and we go back to some kind of thin-client architecture, there will be more thought given to reuse (really, how many times would you want to want to write an app that does dinner reservations).
I love the Gartner Hype Cycle, and we're at the very early stages of it with respect to mobile device apps. Are we at the :peak of inflated expectations" yet? Maybe not, there could still be more hype to come, but we're not far away from the "trough of disillusionment".
When that happens, the need for developers will dry right up. It's no different than the dot com boom and subsequent bust.
