At the moment doors having own button for load family, so windows having, columns having and so on.
As a experienced Revit user I already learned to live with that, but all the new users this seems causing questions why it is like that? Why not one single button through what you can load any family you want no matter what category it is.
I think users know anyway what kind of family they are going to load if they are they using eg. door tool or window tool. So please remove limitations of those load family buttons and make each of them to possibility load any kind of family.
In my opinion it is users own fault if loading wrong category family when using certain tool (door tool and loading window family etc.) Category issues are anyway something what BIM manager defines inside company what category to use for doors, windows and so on. No need to software to guiding this way, causing too much those warning windows and pop-up windows.
Please change features of load family buttons.