Delta did this with my Dublin flight that was supposed to arrive on Christmas morning. (The airport is closed then.) It ended up working out great for us, but I'm surprised that they didn't offer more than just a refund to you. Also, we've been finding some deals just by changing the country of origin. For some reason, some UK hotels accidentally list the same price in USD as they do in Pounds.

I almost forgot, same situation with Groupon for a Haiku restaurant that had closed 2 months prior. They would only agree to give me Groupon credits vs refund. What is crazier is that they are still selling for them on Groupon and Living Social! We passed by today and they are still closed! It seems weird that they didn't take the company down from their site.