First, Jensen didn't "hate" the ending, it took him a little while to get it and then he really did like it.
Second, Dean got the peace he wanted and Sam got the family he wanted.
It wasn't how many "wanted" it. They wanted to see Dean and Cas. Cas' story was over. The last episode was for the boys. I thought it was told well in the time they had available.
I wish people could see this for what it was. An ending and a beginning. As Dean drove his Baby, Sammy led his life. It was a fitting end for a 15-year journey. Jack opened Heaven and Cas helped make it what it was. The boys will be with friends and neighbors, family and each other.
Don't be haters because you don't see the big picture. Enjoy the wonderful journey we had.