I don't want to have to run mods just to get all that functionality.. You list a whole shitload of mods saying "modders already did this", well I don't want to have to download all that crap, mess with modding etc when I can just get it all in a core update to the game.
Adding features to vanilla is good. Some Minecrafters prefer to stick with the original game, like Coe. Plus it means Notch has more splash screens. The Halloween Update was rushed because, well, they needed it to be in time for Halloween. But this Adventure update means they can take ages since they do't have a deadline. More time=more effort=better=42