To be honest, I just don't know if most apps are worth paying for.
I recently switched to Android and wanted to make an app, mostly for fun. But I wasn't sure what I wanted to make. I can't think of any needs I have from my phone that I don't already have met, and I don't want to make a game. I browsed through the Play store looking for inspiration. Maybe I'd see something that would spark an idea, or would make me think "it would be fun to develop a free version of that."
Nothing. I scrolled through hundreds of apps. Didn't find a single one I'd want to use, let alone develop.
Perhaps I'm just unimaginative, and I'm the the patent clerk who quit because "everything good's been invented." But I didn't see a thing I wanted.
Also doesn't help that 50% of the apps are "social," which translates to "we'll rape all your personal information and sell it for malicious purposes."