Spin entry and recovery is, of course, a normal part of pre-solo training in gliders.
I was (still am) a power aerobatics pilot before I went first solo in a glider. Of course I had to do the spin routine too. And I just don't get it.
There's really only one reason why you would spin in a glider and that's the same as with a power aircraft: Mishandling the aircraft so that you get into an asymmetric stall. I think the glider world should go the same way as the power world, and simply teach stall recognition and avoidance, rather than deliberately stalling and spinning.
Having said that, the pressure on the gliding world to abolish the whole spinning thing in their training syllabus is much less. I was shown a spin in the AS K-21 and first of all I was surprised how much effort it took to get it to spin at all, second on how incredibly sedate the spin actually was, and how incredibly easy it was to recover - we lost less than 300' with a full-turn spin.
Spinning in a glider is nowhere near the exciting/dangerous affair it can be in a powered aircraft. Must be because of all the weights (instructor and student really) are all neatly concentrated near the CofG, and the long wings which provide a lot of anti-spin drag. It's not like you've got a massive block of metal sitting at the extremity of the fuselage, or any gyro effects from the fan up front.
Nevertheless, spin a glider on short final, or in the turn to final, and you're just as dead as a power pilot doing the same thing.
So I think the gliding world should follow the power world and focus on stall/spin awareness, recognition and avoidance, rather than requiring students to be proficient in spinning. Leave the spinning for proper aerobatics training, in proper aerobatics aircraft.