That raises a good point; the opportunity cost of an A.I. (at least for us cheap people). If I book an A.I., especially a nice one, I feel like I've already paid for my food. If I then get food from an outside restaurant, it's like I threw that money away. I'm paying twice for food and eating once. An outrage!
So if you're on the dive boat and hear someone raving about the fajitas at Casa Cuzamil, or that octopus linguini at Kondesa, and you think 'Hey, I might like to try that,' are you willing to go pay for it, on top of the extra you paid for an A.I.?
A.I. appeals in that you needn't exit the property to eat. The counter-argument is you may want to, but resent paying twice.