I think its common to have regrets right after surgery. You're still on liquids, feeling run down, possibly still in pain and can have water and protein shakes. It certainly doesn't feel like you're improving your life. But, you are. With time, all those things pass.
You're food choices will not always be so limited. You have not said goodbye to 'fun' foods forever. I was just on a mini vacation and ate ice cream literally every day. I just didn't eat the largest ice cream I could find, with the highest calorie toppings. I came back home and got myself back into my routine.
There is no way I could have done everything I did on my vacay without the surgery. I walked 12 hours a day without pain meds or tears. And I still got to eat a kids size ice cream? Where is the down side!?!