It is considered by some to be a wise idea to have a wired mike ready for use for those cases where the caller has a wireless mike. Wireless stuff tends to fail every once in a while (batteries, interference..) so a backup is ready just in case. And it is good for announcements by someone else. For small dances callers sometimes go down on the floor to help out beginners and having a wireless mike makes that feasible. A head set frees up both hands for gestures, etc. I've occasionally seen callers with headsets dancing and they can still interject an occasional call when needed.