The wheels in those were pretty nice, but I just never cared for the big, blocky tires with light-truck sidewalls MRC supplied. At least they had good tread and decent sidewall detail.
As far as the hinges? Yeah, I could see a market, but I think a pre-assembled piece would be a bit above the average modeler's acceptable 'price point'. Of course you could make one available in kit form (there already are a couple I can think of, a few shown on the thread already), but with working tension springs? Can you imagine the agony of getting your scale hinge all put together, all that's left is installing the spring to make it functional, and then you hear the 'twang' and see the spring you've spent the last ten minutes trying to install fly off into the darkest corner of the room, never to be found?