not out of choice!!!!!
I think most blokes would go for the 'less' attractive of the pick for the reason that the 'most' attractive would be expecting someone to try and pull them. to this 'breed', it is a game, and one where they feel they can reject and carry on to the next. the 'lesser' attractive girls still like to be pulled, be would not play it like a game quite as much and would not reject as often as the 'more' aesthetically pleasing woman.
therefore, in conclusion, men are scared of rejection (generally). we are wimps! perhaps we underestimate our 'range' of pulling if you will, or perhaps we know how women work a little better than we let on!!!