My argument is that the UI requirements are almost always nonsense. I hate launching a new app and trying to figure out a new interaction model or fighting a t

My argument is that the UI requirements are almost always nonsense. I hate launching a new app and trying to figure out a new interaction model or fighting a themes/fonts that fight my needs (font sizes, contrasting colors, etc). Basic stuff is often broken and there's a long tail, if ever, for them to get fixed. They're also the best candidates to break during an OS or other library update. The whole reason OSes give you reusable components is so its easy to implement the conventions users are familiar with. Those are the things that are supposed to be fast and easy. This likely violates the delivery timelines, but Maya, Nuke, and Houdini are all professional, heavily customized apps that were written in their own UI toolkits but were ported years ago to Qt and are cross platform.