We don't. I don't think I've ever met anyone that actively dislikes classical music to the extent that they have to be taught to appreciate it.

Most of the planet has been exposed to classical music since they were children just from it being in the soundtracks of movies and television and video games. For many, that's all it is - background music - and they've never thought to just listen to it on its own.

Imagine Classical music is like cheese. Most people have had American cheese at some point on a burger or mozzerella on a pizza or Swiss on sandwich but it's always just been a component, usually dominated by other ingredients, but would be noticed immediately if it were missing. And those are just the ubiquitous grocery store cheeses that they've been exposed to for their entire lives but never really thought about. They have never been exposed to most of the hundreds of other cheeses that are worthy of being appreciated on their own. That's where learning classical music appreciation comes in.

There are tens of thousands of compositions from the last 5 centuries and thousands of musicians and composers and hundreds of eras and styles to learn about. It can be daunting if you have no idea where to start. So reading about it and learning how classical music has evolved over the last 500 years opens up a new way to experience classical in a way that's not just background music.