Why do washers have multiple spin-speeds?

I usually pride myself on figuring out the answer simply using logic and at a last resort using real world tests - but this is one that just doesn't make sense to me. What exactly do I have to gain by my clothes spinning around at a slower rate?

I thought maybe it was in case of un-even loads, but I just washed a very heavy coat - just the coat - and when it first started spinning and wobbling pretty bad, I thought to myself "Oh boy, looks like I have my answer - shit, maybe I shouldn't have picked 'Extra High!'" but the faster it got, the less it wobbled until it was barely perceptible.

 

I'm not a washing nor washing machine expert. But here are the points I have been told about spin speed.
Higher speed gets more water out of the wash, heavy cotton and like hold water better than synthectic fabrics.
Higher speed uses more electricity and puts more wear on the fabrics and the machine, but spin is more efficent than dryer.
Many machines that have hight spin speed have load balancing feature so they wobble less.

 

Washing machine spin speed efficiency