Many clients wait all year for their refund check. They can't wait to get their hands on it. Some of them have already spent the money and need to pay off their credit cards. Some of them have their eye on a new gadget they can't live without.
There's no more guess-work as to when the money is landing in their account. Your refund tracking page helps them know precisely when it arrives. Your clients appreciate the fact that you're looking out for them.