In recent years I have toyed with the idea that perhaps the greatest contribution to the development of jazz by whites has been just that- the "stealing" of elements of black musical styles.
How so? Music has long been an important cultural touchstone for black people in America, something that confirmed their identity, something that was theirs alone and could not be taken away. When it is assimilated by the general culture in which they live, it loses for them much of its unique stamp and is no longer so very "black".
Recall the comments of Dizzy Gillespie and other musicians of his era. They said that the main force behind the development of bebop was the fact that white musicians had absorbed all previous styles and they wanted to develop a new style that whites couldn't play. And indeed for a while few whites could successfully play the new style. Bop served the same purpose as the ever-changing slang and styles of dress in black culture.
So, it's possible that if whites were not so attracted to black musical styles, jazz wouldn't have flowered into so many forms that we know today.
I also find it ironic, as Diz also pointed out, that after a while bebop was "adopted" by the white intelligentsia and you couldn't make any money playing bop for black folks- they were into rhythm and blues.