"It's not that the users were trying to make me angry; it's that they were ignorant of how to make the app do what they want."

Actually, I think the ignorance is on the developers part.

Users don't care about what some developers may perceive as a sexy UI. Honestly, most don't really even want to "learn" the UI. They just want to get stuff done without having to think about it.

We as developers need to get better about developing software that doesn't require a manual. That doesn't require a user to learn how to use something that in their minds should really be so easy.

Example: don't force a particular credit card entry format such as multiple entry fields, doesn't allow spaces or requires use of dashes, etc. Same thing with date formats. Make your software smart enough to handle as many use cases as possible. If they do something incorrectly, make the UI guide them through the error in an easy to understand way.

We as developers are used to reading through complicated documentation, tutorials, etc. That doesn't mean we should subject our customers to that same pain. Unless your software is at the Salesforce scale, the aim should be to develop it in a way that doesn't require a manual or require your users to dig through a bunch of tutorial pages just to get started.