You are lucky, I often see good prices advertised from NYC to GC. I am traveling from the Midwest and we often have to make a connection in Miami, or Charlotte, or Atlanta - and since we enjoy visiting the sister islands during our trips, that's another airfare and stop(s). Because we like to travel during the fall to celebrate our anniversary, there are fewer flights available.
In general I find airfares to GCM from Chicago cheaper than some other Caribbean destinations. For our upcoming trip, we were able to arrange a direct flight on UA from GCM to ORD for our return trip, but we will have to make a stop on the way down. The direct flight added a little expense but I think it is worth it. After a relaxing 2 week vacation, I would rather not spend many hours in airports trying to get home.
But if this CA special had been available when we were booking it would have been tempting, especially with the 2 free checked bags.