I am mixed about the subject of the "unsung hero". I agree that there have been, and are, many examples of musicians deserving of greater recognition than they got (get); but, personally, I would be careful about attributing too much of the reason for this to forces outside of the musician himself. Musicians can be (and often are) complicated and difficult individuals who sometimes make choices that are not conducive to "success"; some don't even want it. In general, the best players get the attention. This conversation between jazz greats Billy Taylor and Frank Wess addresses some of this:
http://www.prx.org/pieces/20223-billy-taylor-unsung-jazz-players-1-of-2This subject, with the focus on Miles Davis, is particularly interesting because it (inadvertently?) touches upon, and causes one to question, one of the running themes in this thread: the idea held by some of us that the best jazz has already been played, or that a particular period in jazz has the most merit. The two records cited (Porgy and Bess and Sketches of Spain) could not be better subjects for this particular discussion.
These two records, and especially the earlier "Birth Of The Cool" sessions (which were the first collaborations between Davis and Gil Evans) are records for which Miles Davis got top billing when it could easily be argued that Gil Evans was the primary force behind these projects. Yet, these are always considered Miles Davis sessions. When was the last time anyone of us heard any of those records referred to as "the Gil Evans record ....."? Davis was the higher profile individual (to the public) as the rising star of the jazz trumpet world.
But, the real interesting point (and irony) in all this, and how it relates to our reverence for Miles and certain specific periods in jazz is seen when we look at what it was that made Miles the success that he was. The collaboration between Miles and Evans was a direct result of their dissatisfaction with, and a concerted effort to move away from, what they perceived to be the dominance, and limitations of be-bop. As we all know, miles was one of the creators of be-bop.
That kind of constantly forward-looking attitude, with an openness to change, is what made Miles great. Is it not ironic that we revere an artist who achieved great success, in great part, by always moving away from his artistic past; yet, some of us resist a similar open-mindedness?