I will just say, again, that the 12-bar blues, with those three four-measure call and response phrases, offers possibilities for creativity and improvisation that 16-bar blues (often also written as 8) does not. I just finished listening to some old Sidney Bechet and Louis Armstong cuts, comparing their work with 12 and 16(or 8) and they both understood the differences, and used them to excellent effect.

Without going through the whole list of others above, I am guessing that they all understood and utilized the differences between the two forms. And I am out...