For our first trip to WDW last year, we purchased the DDP and really liked it. It was convenient, we got to try a lot of fun restaurants, and it was a good value for us. The service we received at every restaurant was good to excellent -- exactly what we've come to expect from Disney (we go to DL about once a year). It was a lot of food; we are more used to sharing appetizers and desserts, but we weren't required to clean our plates, and we got to try a lot of new things.
This year, no appetizer -- value drops $5-$10 per person -- let's average that $7.
No tip -- let's average meal, drink, and dessert at a TS restaurant $35 -- at 18%, that's a value loss to the customer of just over $6.
So the value lost per day per person is about $13...and the price went down $1. Makes me wonder why Disney even bothered to lower the price that $1 -- I guess for the psychological soothing effect? That and the "we stopped paying the tip and took away the appetizer because you wanted us to!"
Bottom line: the DDP increased guest excitement about Disney Dining, and kept the restaurants booked full. It wasn't making as much money for Disney as they would like (who wouldn't like to have more money? I would!) so they figured out some ways to increase their profit. Removing the appetizers made sense (although many of us have expressed we'd rather have a choice between appy and dessert) because if a party doesn't order them it cuts down the dining time (faster table turnover, less lingering), if they DO order one people are more willing to pay for an appy OOP when they are hungry and first arrive at a restaurants, and appies are typically more costly to prepare and serve.
I really liked the idea of the included tip but the guests pick the percentage (5%, 10%, 15%, or 20%), but I suspect that would have been an accounting nightmare, and may have led to the temptation for a server to forge or change the choice

But it would have solved the problem once and for all of the perception that DDP guests got substandard service because the gratuity was guaranteed. Oh well, that's a moot point now because we have to pay for the tip out of our own pockets. We did NOT benefit at all from these changes, but they are more profitable for Disney.
Because of the changes, we chose not to purchase the DDP this trip. It's still an OK value, but we can eat cheaper OOP if we budget more carefully. It just won't be as carefree and fun

If there is a
free dining promo, great; if not, we'll try to get a discounted rate on our room...