For those with families, it's typically the largest raw $ amount for discounts.
If you figure a family of 4, with 2 Adults and 2 children staying at moderate (so
DDP, values have typically be QSDP for the past few years), they will save roughly (46*2) + (12*2) or $116 per night of stay. The percentage discounts for moderates are usually in the 30% range (at least public offers). Room rates at moderates average about 130-150 per night, meaning a savings of about $45 per night.
So, yes, they have to pay full rate at the resorts, but the fact they're getting just slightly over that amount off in savings per adult, and the savings grows per person on the package (room rates are static per package), means it's quite a good value.
For values, the same family would be saving roughly $94 (QSDP) per night of stay, which is almost equivalent to the cost of the room. (And Value room discounts usually cap out around 25%)
It gets different though once you hit deluxe, as the dining plan amount doesn't increase beyond the Moderate level, but both the room rates and the discount percentage do (thus increasing the return on the room discount).
Of course, it's not for everyone. If, for whatever reason, you have no interest in either the dining plans or eating at the participating restaurants, it's not going to work out in your favor too much.
And personally, I'm not convinced that the dining plans are the cause of the perceived decline, but merely another effect of it. (The root cause would be what prompted Disney to incorporate the plans in the first place, which was most likely lower volume and profitibility. We hear a lot of stories around here how you used to be able to pretty much walk-in at any TS the day of... that's not a good thing from a business standpoint.) But, that's another thread for another day
.
