"The plug & play hobby is almost over. Enter the variable wars :)"Not everybody likes, or has time and attention span, to tweak and adjust. Some like to press the button and not think about it anymore. They are no worse than those who tweak to the end of the world. They just have different approach.
The end of "one volume control knob" era may be coming to an end, if there has ever been that era, but it may be just because of fashion cycles. A few decades ago, amplifiers had lots of shiny knobs, then less and less. It may be time for more. At the same time, real simple-to-use tweaks have been around for decades. They used to come with receivers. "Club", "Church", "Stadium", "Pop", "Rock", and what not. I have not checked receivers in a while, but cell phones/iPods/etc. have such modalities. Changing sound to suit someone's preference has been around, it is not due to the "end of HEA" now.
Wars are never a pleasant experience. Hopefully, variable is negotiable.