Why? Because a song by Metallica fulfills both of them, especially on the older songs which are classics.
Metallica does sometimes also some charity. They are very capitalistic, which I like, as it is their money, but from time to time they do some charity. Last year they gave the earnings from a concert to help build a hospital for kids. Also this years, they gave the rights for free (they usually don't do that) for the same project. Here is the add which shows a lot of sadness.
And here the original masterpiece, enjoy!