Indeed, Perfect Dark already did this with character skins, multiplayer music playlist, weapon, and rule sets. Heck they even let you customize the name for each team color. Also, it was a game that allowed you to pick up all of the guns in a weapon set while still enabling you to quickly and seamlessly select which gun you wanted to use without having to cycle through them. There was even a menu where you could quickly give orders to AI teammates (a lesser known but extremely useful feature).
Really, the original PD was a game that was before its time in many ways (though behind in core gameplay mechanics).
I would be very happy if HVS used even a fraction of the features mentioned above, especially the multiplayer music playlist options.
Uncharted 2 Machinima Voice Actor. Currently playing Sully and Lazarevic. Add me on PSN if you want to get involved: Geo_Chronic.