Just my opinion, but...
The "live TV" thing is vastly over-hyped. I've been on B6 flights before, and I'd prefer movies anyday. Any time the aircraft banks, the signal is lost mometarily, which is somewhat annoying after a while. Also, you get local programming for that time of day. For instance, I flew SEA-JFK on a redeye. Because it was 1:00 am, I got about 20 channels of infomercials. Not very entertaining.
By contrast, I just flew LAX-KIX on JAL. They had the private movie channel option, which was a far better deal. Even on a 12 hour flight, I didn't run out of first-run movies, which made the trip pass much quicker.
I'm sure the live TV is much cheaper than having a selection of first-run movies, so economics undoubtly plays a factor here. Every airline has to decide what level of service they can reasonably provide for the ticket price they charge, and B6 offers very low ticket prices.