It is a while ago since I stayed, but this is my view: I guess this depends on your desire to eat at the nicer restaurants and how much liquid (particularly alcohol) you expect to consume - bearing in mind some mains at the restaurants are over USD450 (excluding service/tax at about 22%). You can certainly eat for less than USD300/day if you are careful, skip lunch, don't have wines/alcohol, and don't eat at the seafood or steak restaurants for dinner (e.g., stay with the standard hotel restaurant).

The most recent menus are here, I believe (was a valid link in 2022), so you can take a look and think about what you'd prefer: https://www.taptastego.com/MLEJS/

And for prosperity here, unfortunately I don't seem to be able to upload the menus I was given as PDFs (and they're from 2020, so pretty aged now), but here are the PNG versions. You can see from the prices, all excluding the 10% service and 22% government tax, that you can easily spend a thousand dollars on a dinner for two people, or you could be careful, avoid the most pricey options and save money and probably eat for USD200 for two. Personally I'd say that the all-inclusive just removes the worry about how much things cost, lets you set a fixed price up-front, and lets you snack, graze and drink through the day. Anything less than that, you are just going to need to be more careful - but that is easy to do if you hang around in your villa/bungalow, and don't go out from it much.