That's a pretty cool idea, but honestly I don't see much point to it. Have you seen the prices of even the "cheap" circular mil style connectors? Granted, if I was removing my carpc every single day it would be worth it, but generally I go at least a year inbetween having to do things like that.
Don't forget you're not going to be able to pass VGA/USB through the same connector as your monitor/peripheral power, not to mention audio without issues unless you pay for the individually shielded contact style connector. You CAN get that style connector, we use them at my work all the time. It'd be amusing to have a $400 computer with a $200 connector