Hairstyle should be skinnable and thus completely customisable. The skin interface should be one easily usable by end-users, not just developers. Ideally there would be a 'Builder' that would allow me to drag&drop objects to where I want them to be, and define the succession of pages. Failing that, some kind of markup or script language.
I am thinking along the lines of the designer for the Philips Pronto remote control - where you can position graphics on screen, and control which function they perform. In the MC world, this would mean I could create my own graphic (or use a supplied one) for 'Audio', then configure that this goes to an Audio page, on which I configure there are buttons for Album View or Artist View, which I configure to give lists of the respective items, etc.
I believe that giving the user complete control like this would remove a large number of future feature requests - this is something I feel strongly about for the whole of Media Center. Spend time opening up customisation to the user (as I've mentioned in the general v10 features thread, re macros/scripting/complete control of toolbars), and they can build the MC they want, and post their customisations for other users. Then J River can concentrate on upgrading the core functionality and features, and let the users mould them as they see fit.