[jlind]

>sometimes projects do start with very simple UI and focus on application functionality, so it could be hugely helpful to consider the context of UX.

I've found this is one of the more powerful and easy ways to prevent feature creep, at least for the smaller/shorter projects I have worked on. When I start with a UI, I find it's easier to ask what the bare minimum of a) inputs and b) feedback/guidance for the user that needs to exist. In the projects where I've started with a backend first, I often end up having to create more noise on the UI side to complete it.

I think this just goes back to your first point, how developers are more effective when we're involved in creating the requirements. Practicing good design is going to be more effective when you choose to focus on it up front, instead of relegating it to something to check off a list when the application has been developed.