when dancing balrrom why does a dancer need to master the different dance positions?

Answer 1

Several reasons:
1. If you dance everything in closed position it becomes pretty boring.
2. If you dance everything in one position it will look rather stiff because change of position is what brings dynamics to your dancing.
3. It is nearly impossible to dance the entire dance in promenade or in outside partner.
4. You have to learn to distinguish the difference between the positions really well or else you will be bashing knees with your partner's all the time. No matter if you lead or folllow. Knee-bashing comes from not knowing the positions and transitions between them.

Answer 2

Ladies need to learn them for the very simple reason that they're going to be led into them, and if they don't follow the entire dance will be interrupted. Also, see below:
Men need to learn them because dancing only in standard position, never in promenade, for instance, would be quite boring, for one, and the added repertoire is very useful with floorcraft, and who hasn't been boxed in by other couples on the floor?, plus, it's the man's job to make the lady look good, and I can't imagine a tango without the sharp changes of position that really let the lady show herself off.

Answer 3

will answer your question with question: who likes to dance with a partner that becomes out of step, or when singing, who wants to duet with a singing partner or back-up when said someone is not complimentary but just out of tune? Of course, that is for those with practice sessions. What about those instantaneous life's roleplayers? Hah, I tell you, it's God guiding them, what to do, like a perfect first-true love fairy tale dream that keeps striding itself for reality in its search for freedom and happiness. Hope I've helped?