This is definitely a letter that, prior to the Internet, would never have been written. It goes out of it's way to not appear to be a "dick" and appeal almost in a friend like way to make the person receiving want to do "the right thing" by not making a threat. I've never seen a letter written like this in this situation (having received them and seen many over the years.)
I wouldn't have let an opportunity like this pass. I would have seen what JD would pay to redo the cover, let them do it, and garnered even more publicity. And maybe pocketed some money by subcontracting the labor. The cover design isn't that critical and the extra press mention would most likely drive more sales. As only one example they could have said "it will cost me $5000 to redo" found someone to do it for much much less and pocketed the difference AND gotten more publicity. And I've done things like this is the past with large corporations they will write a check to dispose of a problem they won't say "um we want to have our artist do it". If the price is reasonable they would just pay. (The only question is how much I would have started much higher than $5k that is arbitrary..)