EMG, I'm going to side with you on this one. Everyone posting has been correct in much of what they say. I am also not someone who expects (or wants) something for nothing. However, you are a repeat customer who has shown some loyalty to CCL. That should count for something.
I assume that you do not a history of complaining about with CCL either onboard or after you cruise.
So would it have really been so bad for CCL to make a small gesture to at least say thank you for speaking up and pointing out issues, even if they are somewhat common issues for cruise ships?
A simple bottle of wine or a free dinner for you and your wife at the dinner club on your next cruise would have at least been token acknowledgment of your complaint.
The other side of this is that now there may be first time cruisers out there that will read the two letters and plant a negative seed in their head even before they board their first Carnival boat.
Those gold cards they give repeat guests really should mean something.