Big ol’ +1 from me! Especially to the single select field.
The workaround from @James_Steed and @Noel_Howell is nice, but you can’t group by that formula field in the Kanban view.
Like @Dan_Weaver pointed out, it looks like we’re stuck with that ugly “Uncategorized” stack. That could easily be resolved with a default value for single select.
If you really wanted to get fancy, you could go so far as to have a “field required” option on fields with a defined default value. If the user tries to delete the content in the field, it could revert to the default value. And add an option to disallow “create a new option named …” so that people can’t accidentally add to the single select options with a typo. In some cases I prefer to be forced to customize the field type, in other cases creating the new option as I add content is nice. Toggling that option on or off would be cool.
But now I’ve gone off the deep end. Those extra things would be nice to have, but the only thing I actually NEED is the ability to set a default value for a single select field.