I am in the process of investigating bringing in a cooler to the parks for our lunches. I can get/make our lunch meat for the week for the cost of a single meal at a QS restaurant. We won't pack every meal, but a majority we will. The more I can save on trips means the more I can take trips. Would I rather spend $600 a week and take 3-4 trips staying in a multi-room condo/villa/house or spend $1,200 for Pop Century in a small studio and only take 1, maybe 2 trips?
The only benefit of staying on site now for me is morning EMH. That is no longer an important benefit because we avoid that park now. You can enjoy most things at evening EMH except getting on an attraction. You can do all of the resort activities except swim if you visit the resorts. Even then, swimming is not blocked from most resorts.
We pack pretty much every meal. My wife and I are pretty strict on nutrition, especially my wife (even on vacation). We also don't want to spend a fortune on food. We go to the local Publix grocery store and buy food just like we would at home. We typically eat breakfast in the rental house, so we never pack that. But lunch and dinner are almost always packed. It's pretty uncommon for us to be at the parks so long that we need to pack both meals, so it's usually just one. For example, if we get to the parks at 10:00am, we usually are done by 5 or 6pm, so we only pack lunch. Or sometimes we go to the parks at 2pm, so we only pack dinner. We pack everything...main course, veggies, snacks for the kids, sodas for us (diet, caffeine free of course...), dessert for the kids, etc... A lot of people seem to think we spend hours cooking and cleaning so that we can do that. In reality, it's not even close. Maybe 20 minutes per day, which we do while we're having breakfast and morning coffee anyway. For dinner, we usually cook in bulk once, then bring leftovers. Lunches take a matter of minutes to pack, and the kids help. I didn't actually tally it, but on our recent 17 day trip, I'll bet we spent a total of $400 in groceries, to feed a family of 5. Maybe it was a few bucks more, could have been a few bucks less...I know our initial "stock up" trip to the store when we got there was around $225, and from there we just supplemented things...plus we had a good amount of food to bring home, so it didn't go to waste.
It's also easy to transport to the parks. We have a very large soft sided cooler bags. It's the size of a plastic cooler on wheels, but much less cumbersome. We pack it strategically, using ice packs or hot Thermos containers, depending on need (sometimes we do both...hot on one side, cold on the other). Yes, it's fairly heavy when we first pack it. However, I only have to carry it from the car to the tram for the ride to the front gate. From there, we have a small umbrella stroller that we bring. We sit the cooler in the umbrella stroller, and the handles for the cooler bag fit nicely over the stroller handles to keep it from falling out of the seat. We then push the stroller into the park, easy as can be. Normally, we'll park the stroller near where we plan to eat lunch/dinner, leave it there and come back when we're ready to eat.
That's not to say we never eat out. My wife and I very rarely do, maybe twice on a two week trip, but we'll buy snacks and desserts for the kids from time to time. We're very happy bringing our own food in and it works great.