What evolutionary advantage .....?  

Never mind.  Sweaters.

Funny how an animal that amuses humans, once domesticated, can expect at least a century of increased livelihood.

Compelled to dig deeper:

"Angora wool or Angora fibre refers to the downy coat produced by the Angora rabbit. While their names are similar, Angora fibre is distinct from mohair, which comes from the Angora goat. Angora fibre is also distinct from cashmere, which comes from the cashmere goat. Angora is known for its softness, thin fibres, and what knitters refer to as a halo (fluffiness). It is also known for its silky texture. It is much warmer and lighter than wool due to the hollow core of the angora fibre. It also gives them their characteristic floating feel.

Angora rabbits produce coats in a variety of colours, from white through tan, gray, and brown to black. Good quality Angora fibre is around 12-16 micrometres in diameter, and can cost as much as $10 - 16 per ounce (35 to 50 cents/gram). It felts very easily, even on the animal itself if it is not groomed frequently."

So it might be possible to clip a nice felt beret right off a living ungroomed angora rabbit. 

Thanks for the extra research Geege. I'd love an angora rabbit beret!

Source is the Reddit thread on Angora rabbits:

http://www.reddit.com/r/WTF/comments/1mpt0p/this_is_a_angora_rabbit/

Wait but Why -- The bunny manifesto:

http://www.waitbutwhy.com/2013/08/the-bunny-manifesto.html

These little bastards chew threw electrical cords. They get high off the buzz.

That explains a lot. Electricity is a bunny drug!