Your serious belief is that everybody just happens to like things? There are no structural forces that influence what gets created, promoted, or held up as "great"? That in the arts there's nobody with more power than anybody else?
I suppose by the same token, the highly improbable demographics of Fortune 500 CEOs, legislators, and faith leaders are just some statistical quirk?
Please tell me more about this world you live in. I would like to visit sometime.
> Should they required to spend time on things they like less?
This is where I'm not getting you. What are the powerful forces imposing the canon? Who is forcing you to listen to music (or read books, or watch movies, etc.) that you don't like?
What is considered great arises out of organic, decentralized processes. There's no central bureau of music that requires everyone to listen to Mozart because they decided he's the best.