I like changing the UI skin from time to time to get a different look. A long standing frustration of mine is having to re-adjust how the media library's panes and columns are displayed when changing between skins I had previously setup (or when changing between the usual and maximized window sizes in the same skin). It is rare that the same, less than maximized, size is appropriate for all the skins in my collection. While some positioning aspects are saved on a per skin basis in the "studio.xnf" file (for the last overall size used), other positioning aspects are saved in the "gen_ml.ini" file on a global basis for all skins.
The need to re-adjust column widths (and other things) to best fit the overall space available in the ML window to eliminate or reduce the need for side-to-side scrolling (while still being able to see all, or a useful amount, of the info displayed) may be a reason why some users don't use the media library. Although, bigger reasons are probably a general reluctance to change any of the app's defaults and the need to ensure each media file contains the minimum, accurate, metadata tags needed to make the ML useful.
At a minimum, saving all possible positioning aspects on a per skin basis (for the maximized and the usual overall window sizes) would be greatly appreciated, imo. Furthermore, saving the skin-based ML content categories used (e.g. the specific sub-panes and columns used) on a per skin basis (for the maximized and the usual overall window sizes) would also be helpful. I understand that some of the ML content categories are selected in general preferences and are not dependent on the skin being used.