Should English teachers call on shy students?

Last Saturday in your comments on the strength's and weaknesses of Reader's Theatre and a few weeks ago when you all critiqued my vocabulary teaching techniques, I noticed a common theme. Quite a few people wrote that the weak points of students acting out their class reading in front of class or a teacher using actual students to introduce new vocabulary (example: look at Naomi, she has LONG hair and Takeshi has SHORT hair) is that shy students will not like such activities. I was wondering do you think a teacher should encourage shy students to speak in front of the class or do you think that English teachers should just leave shy students alone? Why? If you think that English teachers should encouarge shy students to speak in front of the class, how can a teacher do this?

The above questions are optional. You DO NOT HAVE TO ANSWER THEM but I think your opinions would be very helpful for me, current English teachers, and aspiring English teachers.

Have a nice weekend!