One of the rules in business is to market to the hoardes a unique feature that'll make you stand out from the rest.
You'd have to admit, to Mr and Mrs Jo(e) Public that onboard live satellite TV would have to appeal to those who don't have it at home, and who most likely are only discovering the joy of flying.
Very clever marketing strategy really when it is all said and done.
For those of us who don't value the novelty factor, it won't really make a difference.