A high light of the days when I attended the national Acoustical Society meetings was a debate between Edgar Villchur (sp?) and Paul Klipsch during which Klipsch said "I don't care if you push it with a broom handle, you still have to move the air." Of course, we know who won that debate from a sales standpoint. I think stereo ended the days of the great corner folded horns.
It's a testament to the engineering wonder and sonic impact of the Klipschorn that it's still made today, largely unmodified, 70(!) years after its initial launch - a feat I believe no other speaker model can rival. Mr. Villchur's acoustic suspension principle has had a lasting effect as well in many different incarnations, but its sales pitch of lower distortion at low frequencies has in effect been foreshadowed first and foremost by its reduction in physical size - an aspect that brings with it (in conjunction with much lower sensitivity) a set of new audible limitations.
Many audiophiles not in favor of hornspeakers seem hellbent on pointing out their "colorations," all the while being oblivious to the shortcomings of direct radiating speakers that can be heard as an absence of core traits such as dynamics, scale, ease, speed and overall physical/emotional impact. One anomaly "popularly" comes in the form of an alteration/addition to a signal (horns), whereas the other goes as a negation (direct radiating speakers); what the latter lacks I feel typically weighs much more as a coloration than the former, so there we go.