This might be a stupid thought, but I wonder if there's a psychological issue at play for iPhone apps in particular where people subconsciously think small form factor = pretty simple = pretty cheap.
Of course, the reality is usually exactly opposite.
You're absolutely right. "Simple to use, simple to build" is another thought in people’s minds. They don't realize it's actually harder to build something that's simple to use.
I think many people assume that iPhone development is simple is that there are so many apps. Many of them are low quality and are just web apps crammed in a web view.
Of course, the reality is usually exactly opposite.