Bass clarinets are cylindrical, yet I have yet to play an ancient one (I've tried several, under very close supervision) with a single vent that works right.
Then too, with the half-hole hole through the first finger, left hand finger plate, modern horns have three such holes.
Soprano clarinets have a single register key, but you "pick" out the altissimo register with the vent and a half-hole fingering on the upper joint. Marchii (sp?) also produced a horn (through Selmer) with a second register vent high up on the barrel.
Against all of this, there is the added complexity that such arrangements create. Many a school bass clarinet has a completely flawed register system due to the long connection rod on the rear of the instrument, something that invariably gets beaten all to crap by students who share (but who don't care for) a single instrument. The "super oboes" have their complexities, and our friend from Seattle would (if all of his mechanism was realized and automated) would suffer his own brand of hell.
Just because you can get a patent doesn't mean that it is a commercially viable idea. All that needs be proved in the examining process is that an invention is novel (i.e., that particular application has not previously been thought of and patented), and is not obvious. Nothing there about commercial viability.
Like I said before, I'll not be pining away after a 'Broctave' key sax any time soon...