Sky's business model is that the subscription + the adverts pay for the service. If they got rid of the adverts, they'd have to raise the subscription. If they got rid of the subscription, they'd have to increase the adverts (like with FilmFour a couple of years ago).
I refuse to consider Sky as I refuse to have a monstrosity stuck on my roof. I'm on free cable, zero down and zero per month, about 30 channels of rubbish and half a dozen channels with occassional good stuff on from time to time.
JGH