I'm 32 years old. I've been to war, dealt with more than a couple life or death situations, and made sacrifices for loved ones that people just shouldn't have to make. I've been to 5 different continents, interacted with people of many different nationalities and religions, and read heavily from religious and philosophical texts from all over the world. I am a very cultured, very mature adult. I am not at all uncomfortable with thought provoking, mentally stimulation situations, and I wanted a boss fight.
I don't play many video games. I bought one game between ME2 and ME3 and it was a strategy game. I play video games because they are fun, because they are a light hearted and simple minded escape from real life. I don't NEED a video game to feel mature or deep. I already know I am. For some people, those who make video games their life, an occasional detour into realms of deep thought may seem like a fun excursion, a mental exercise that you can reflect upon, and then tell yourself, (and anyone on the forums who will listen) how mature you are for liking it.
Some of us, however, already live our lives in deep thought in a very real and very mentally stimulating world. When we play video games, we want the hero to ride of into the sunset, or, if it fits the theme of the game, to make a heroic sacrifice that illustrates the positive traits that are far too uncommon in the real world.
So don't come here and tell me that I am a child for wanting a boss fight at the end of a game, because when all is said and done. I'm going to put down the controller and go back to the real world where you can't face down the embodiment of all your problems and defeat them once and for all, whereas you are just going to start on another game, and get some other happy ending somewhere else.