Speaking only for myself of course, I was pleasantly surprised at retirement to find that I could afford to do cruises now and then. However, after a lifetime of watching my spending very carefully I find that I can not enjoy the experience nearly so much when I pay by the drink. Have-it-All works for me by allowing me to just enjoy myself without thinking about it.
That said, I personally can easily come out ahead on the deal when the credits are figured in, but my wife barely drinks so I am pretty much guaranteed a net loss overall. We both agree that it is worth it to us for convenience and enjoyment, which is the reason we are there.