A media player could be a headless jukebox (that is, have no monitor or keyboard) holding all your music, a home theater with 7.1 audio and a digital projector, or a simple bedroom movie player.
Many of us don't care what brand of oil goes in our car as long as it does the job, and we don't care what label is on the DVD player when we have a movie night at home.
The BD + system protects movies if pirates should develop mod chips for Blu-ray players or develop Blu-ray player software that allows movies to be copied.