It's cheap insurance. It will mitigate moisture and molds as well as radon. It won't make or break a deal, and it will add to the resale value. Ten years from now, it may be a law. I'm glad to hear from lenders that it really won't hurt builders and will make the home more sellable.
Litigation is very expensive.
One question that's come up concerns using a fan running constantly. You may not need a fan if the system is designed right. Generally we recommend that you build a passive system and add the fan only if needed. Bob Fowler, the leader in international code development, was there. So was Pliny Fisk.