I am not that statement is true anymore. I think that most men prefer brunettes, however with so many colours on the market, a lot of woman have at least tried to go blonde a few times to put to test that experiment. I myself have not. I am not a fan of blonde hair.
I think like any other superstition that started long ago, it just passes through decades.
What would be interesting is to ask blondes if they had more fun, lol or just men to answer and see what kind of statements you get.
I think it all boils down to the personality that comes with the hair.