They worked as a marketing tool when young males where pretty much the only market the companies where trying to attract.
Now, as gaming becomes increasing "mainstream" (which really means; as the 10 -25 year olds continue playing games throughout their life and an increasing number of females join the gaming community), they are probably now reducing sales overall ... if I was an average 13 year old girl just starting to get into gaming, seeing these women drapped around, would more than likely dissuade me from remaining in the community - scale that view up by the millions of potential customers the games companies can see ...