I would guess, after this promotion ends, and the dust settles, WDW will determine whether or not the promotion is worth having again. I would guess the original thought of Management was "If they don't have to spend money on food, they'll spend it elsewhere," and their eyes lit up with visions of all that Disney merch, some of it marked up to ridiculous extremes-flying off shelves, thus also making room for more "limited edition" merch.
However, one of the harsh truths of our economic climate is that not everyone can afford a Disney vacation. Politics aside, it's no secret that wages are not keeping up with inflation, the minimum wage hasn't been increased for far too long, and the price of a Disney vacation usually doesn't get cheaper. I would bet many visitors-not all, but not just a few, either-would not have been able to afford a Disney vacation any other way. Even with the promotion, they're scrimping to make it a reality. I know; I have relatives like this. They intend to spend as much on soveneirs as they usually do, because that's all they can spend. They don't look at the money saved on the free dining plan as "found money," and would not have gone at all were it not for the promotion.
Meanwhile, you also have a good chunk of families who are occasional visitors. WDW isn't a yearly thing, but it's not a once-in-a-lifetime thing either. They might normally have to visit on a stricter budget, but suddenly they are able to visit for a much more affordable price. SOME people might opt to spend that money on souveneirs. But SOME people might opt to spend that money...on a longer vacation, with more free dining. I mean, I like a ridiculously expensive Disney sweatshirt as much as the next cat, but if I had a choice between spending upwards of 40 to 50 bucks for each member of my family to get a sweatshirt, OR using that money for one more night in a resort, I'd be tempted to say memories will be more important than things. And still others might be tempted to just take those savings...and keep it.
As I said, if the promotion worked out for WDW, we'll know because they'll do it again. But if it's the last time we ever see the promotion, we'll know that it may have been a great perk for the visitors, but a bust for the company.