The point of making films is to make money, and the Avatards will be sure to part with more of it for any new piece of crap that is added to it.
If they had wanted to give people something good, they would have made a greatly different film in the first place. But it would seem that people want simplistic crap, since that is what most people go to see, and therefore makes the big money.
If you object to them adding footage, I suggest you not go see it, or buy it when it comes out on BD and DVD. But you will not stop others from spending their money on it, no matter what you think of it or the people who want to see it.
"Real value" is something that is a fairly alien concept to Hollywood, so you ought not expect it of their productions.