I question how many riders have the required $500,000 limit. I've owned an insurance agency for 34 years and most people want minimum limits, this could prove costly if you check the block verifying that you have required coverage.
Personally for the 40some odd dollars I will keep the coverage that comes with the pass. Don't forget you are also buying legal defense when you buy a policy of insurance, how far does 40 bucks get you in an attorneys office?