Here is the problem with eating offsite, there is the time is money argument to be made. Let's say it takes you 3 hours per meal to go offsite to eat, that is 3 hours away from your vacation time. Now to determine a dollar value for that time, well you could use your salary and figure out what your off time is worth, but honestly that will vary for everyone to an extent I can't even start to examine it, so let's go with based off the cost of your vacation.
So let's assume that for a 14 day trip you manage to get the price down to $3,500 for two people (Those with DVC is a different story for pricing, but this is doable without the dining plan for two). Let's assume the parks are open 12 hours each day for ease of calculating, that breaks down to about $20 per hour, meaning your cost of those three hours is at least $60. The reality is it will still cost you around $20 for the two of you to eat, so now we are at $80 in cost for a single meal, not counting transportation costs. The standard dining plan is about $75 per person per day and gives you one counter service, one table service and two snacks per day plus the refillable mug and if you drink the meals include alcohol.
Remember while the dining prices have increased, the dining plan prices have not so far.