Wife and I went on our first trip back in 2010 and had the quick service dining plan then. I *think* it had an extra snack with it then versus now but I may be wrong. Anyway, we never went hungry, had several snack credits to use at the end, and felt it a pretty decent value then so decided to add it again for our 4-day trip end of this month. Looking deeper into it recently, I see where it's definitely not a steal of a price but pretty fair.
Is it possible to spend LESS without the plan? Absolutely. But for what little extra it may possibly cost us, for us that small price difference is worth not worrying about it at all. If on a fairly tight budget, go without the plan and stick to whatever your budget may be for each day. If you're willing to (possibly) spend a small amount more to not be concerned with it, or you're interested in the higher plans for frequent table service meals, get a meal plan.