A huge reason that I prefer timeshares over hotel rooms is the ability to make your own meals. Not only can you save a bunch of money doing it this way, but you tend not to eat as much, and certainly not as much junk food, when you eat at home.
What I don't like about meal plans:
1) You are limited to certain restaurants. Who wants that kind of limitation? I don't want to plan my activities around pre-paid meals, or even free meals. The joys of traveling include both exploring the broader area AND eating at local restaurants. Meal plans stymie both of these.
2) I tend to book a lot of activities, such as land tours and snorkeling trips, so we're either physically away from the resort during meal time, or breakfast and/or lunch is included in the activity.
3) Meal plans include breakfast. I don't know about your family, but our family wakes up at different times, so we tend to eat when we get up. It'd be a minor PITA to have to wait to eat until everyone was awake and dressed, then assemble to go to breakfast together. So I actually PREFER eating breakfast in the condo.
Plus, when you isolate the cost of breakfast, the ridiculously high cost becomes even more visible.
For instance, on vacation, this is our grocery list for one week for our family of 4: coffee, juice, 2 dozen eggs, veggies for omelets (mushrooms, green onions, 1 tomato, 1 red pepper), ~3 pounds of potatoes, 1 pound of sausage, 1 pound of bacon, 6 bagels, 8 oz of cream cheese, a quart of vanilla yogurt, margarine, and a boatload of fresh fruit.
Even if we bought this at the most ridiculously overpriced on-site resort grocery store, in order to justify buying a meal plan, that grocery bill for just those items would have to exceed $1100, which is what $40pp per meal per day comes out to. Even if you juggle the numbers around, and figure that you're spending ~$10pp per day for breakfast, then that balloons the cost of the other two meals to an average over $55 per meal.