It is just not about the music, it is the whole package. Let's see, watch a typical video with a symphony orchestra performing some random concerto by Friedrich von Beet-Shuzart.

What do we see here? A grave audience, sitting stiff in their chairs. An even more grave orchestra, everyone dressed in black, bow moving up and down and up and down, everything conducted by en elderly man in a tail coat, waving with a little stick.
Let's be honest. This is not too sexy, right?
And the classical nerd closes her/his eyes, gets swept away by the beauty in the music ... the others think this is relaxing, at the best. Or annoying. Or just plain borrrringgggg.
Now, lets shift the wrapping. Add emotions, tons of them, and let the music be the soundtrack to a story. Like this, for example:
Let's see how many who fall asleep now, although the music is, indeed, soothing.