Interesting discussion on the blues. As a player who is not a blues player, but plays in a band that gets lumped in (and marketed) as a blues band, I play a lot of festivals. And I was talking about this very subject on a radio interview yesterday. Blues these days is really 'in a box'. You have to wear a costume (a bowling shirt and fedora helps), play a certain type of guitar (not invented after 1962), and use a certain kind of amp.
Performers do the 'entertaining' thing, rarely deviating from the type of performance that BB King was doing in the 50s. And if there are any players out there adding anything new to the blues, I haven't heard it. I don't define the blues as a chord progression, a series of bends with the pentatonic scale, or guitar faces at the right time, though. Many do, which forces the once-revolutionary/rebellious art form into a stagnant lounge act.