Just another random question I'd like to put out there:

Why don't clarinets have closed keys?

*Random video of clarinet and soprano sax played at the same time*

http://www.youtube.com/watch?v=BdTZGGZ4oa8&feature=related

Lol! That's what made me think of this...

Some clarinets do have closed holes. Many old time jazz players who doubled on sax, flute, and clarinet played closed hole instruments.In fact there are a few known names who will make professional level horns on special order.

Having open holes certianly opens up your ability to play more things; half covered holes, quarter tones, and microtones. The open hole clarinet gives more opportunity and that is the reason to have it open holed. But, yes, there are closed hole clarinets.

Thanks John!