TP you are going way out on a limb on this one. The manufacturer will charge for everything extra over a bare bones car. Bikes do the same. Add a sun roof or a built in bike rack or a trailer hitch and you will get charged for it.
Chrysler used to charge extra for the car radio as an option. They got hammered for it and so they made them standard, and tacked the price on at the base price. That is just how it works.
No one would be happy to pay for a bike rack that 99 percent of the owners would never use. It would be like making a car free person buy an oil recovery pan in case they ever helped someone change their oil.