TRX: Innovative thinking for the Robotic Combat Vehicle-Medium (RCV-M) class

Always wondered why the USMC went with the JLTV as the carrier for its NEMISIS. Seems like a purpose built robotic vehicle would be an easier and lighter solution. Perhaps commonality played a role, perhaps speed to development. Besides carriers can be replaced can't they? I don't know the specs of this beast but it would seem like the perfect anti-ship/land attack missile robotic carrier.