September is normally a slow crowd time, due to hurricane season and kids going back to school. On top of that, August is usually pretty warm in Orlando, so it's not like you are going to escape the cold up north at that time of year. So Disney has to offer something to fill rooms. I can assure you that Disney has priced rack rates accordingly, along with park ticket rates, etc.
Free dining can be a great deal, but as others have said, it's not as great as some of the other discounts Disney periodically offers.
Also, to those who say they don't 'eat all that much food,' I sort of thought that too, when the dining plan first came out - or at least we didn't eat an appetizer, entree, dessrt in ONE SITTING.
When we actually tired free dining we found we were able to adjust pretty easliy. You only get one QS meal and one snack beyond the TS meal. I'm really quite certain WDW has adjusted portion sizes since the advent of
DDP, while also adjusting oop prices upwards. Add to that - this year the TS part of the DDP doesn't include the appetizer.
We don't get dessert at every meal ordinarily (non DDP), but we usually get one QS meal, TWO snacks, and one TS meal per day. You can also use the credits to dine at a high end place too.
One thing that DOES make sense - is to arrive early on your first day and stay late on your last. You get dining for each night of your stay, so making full use of it on each of those half days matters. On the last day, you can use up those leftover snack credits for 'lunch.'