Under 4.6.0+, the prefs panel is open to all user levels. Does this give us an opportunity to make strides towards making it easy to add per-user or per-priv-level theme prefs?

Adding prefs to plugins is fairly simple as it is now, and there's better control over which groups of users see them. We could add a better API to make it simpler still. Would this be of benefit to themes too? I'm thinking of things like allowing auto-growing textareas, or turning on/off panels or features without end users having to hack files.

To be clear, It's already sort of possible to make theme prefs if you know PHP. I'm proposing we make a nifty API to make it super simple to register everyday toggle prefs and select lists, etc. And add mechanisms to not only allow plugins to register prefs but also themes.