For the original registrant, next time they step up to the crease in a domain dispute it will be a black mark against them to have lost earlier. This will make it harder for the original registrant to hold onto his good names.

It may even make him stand out as a target.

There's a lot to be said about this. It's usually worth defeding an INDRP (or any domain dispute) even if it doesn't make economic sense (the cost of the domain is less than the cost of defending), as losing the domain can set a bad precedent that can be used against you in future disputes.