'will thorough documentation better render the psychology, spirit, and "essence" of a specific musician? '
absolutely - but even more so in jazz, because it's not just esoterica but potentially great music - so we get to enjoy it at the same time as it increases our understanding of a great artist -
'Speaking hypothetically, is my understanding of Dolphy inferior for having not heard the Brownie sides? Of course, limited familiarity with an artist's discography impairs knowledge of history, technical development, etc. But--for the neophytes, the laypeople, issues of economy and choice--is it all really the same?'
well, I would assume that if you are posting on this site you are not a neophyte. And yes, your (our) understanding of Dolphy is virtually impossible without hearing anything from this middle period. Since CHuck will not enlighten us about those mystery recordings, I will assume that all we have in the early Dolphy discography (and I have done the research) are uncertain big band appearances in the late 1940s and than a skip to 1958 with Chico Hamilton. It's similar to problems with documentation of Lester Young - we have nothing real early, only the first mature playing. So, given the opportunity to not only fill in the historical blanks but also to hear what will likely be great music, I would regard these home recordings as essential.