First off, the blower motor resistor is what allows the switch to give you variable fan speeds for your heat, defrost, and air conditioning.
Second off, it might be worth replacing. Your blower resistor has a greater potential for failure. Your heat will come out at one speed, high. If your dealer isn't that far away, and you can do without the car for 30 to 45 minutes, then do it.
This is just my humble opinion, if your confident that it won't fail, then don't waste the time to have it replaced. In my experience, though, if FORD recalls it, they have a reason. Failure of this part seems to be pretty common, if that helps you answer your question.
