Usage of "he don't" vs "he doesn't"

"He don't" means "he doesn't." I'm not sure what you mean by "the artist used it for better sounding." If you mean that the artist did it to fit the word into the rhythm by eliminating a syllable, that seems unlikely. If you mean that the artist did it to make the song sound grittier or more natural to the voice or character(s) portrayed in the song, then, yes, that seems likely.

Using "he don't" for "he doesn't" is informal English and particularly used in certain dialects. You hear it in cockney, a London dialect. You also hear it in ebonics, a dialect of African Americans. It is not limited to these dialects, but the usage is very often associated with being working class or low class because the dialects that use it tend to be working class or low class.

While the usage is longstanding, hundreds of years old even, it remains widely frowned upon as being illiterate, an indicator that the speaker lacks education. I say "widely" because that isn't always true as even Harvard grads have embraced this usage in their own day-to-day speech as part of embracing the dialect of their heritage. Nevertheless, when it comes to mass opinion, if there are degrees of informality, saying "he don't" is regarded as highly informal, teetering on vulgar albeit not profane.

Incidentally, you also see it used in eye dialects, in fictional writing that uses spellings and phrasings that reflect how a character actually talks or thinks. Mark Twain used "he don't" quite prolifically in books like Tom Sawyer and The Adventures of Huckleberry Finn.

Yes, it's usually done for better sounding as you put it. There are many such incorrect phrases in the songs of Pink Floyd too, for example:

I don’t care if the sun don’t shine (Jugband Blues)