Most are probably indifferent to it.
I *prefer* having onboard screens, only b/c it provides me options. I can work on my decks during the flight and watch something on the IFE at the same time - no additional device required.
BYOD hurts folks who like to split their time between their main device and IFE (and of course theres no room for a third device in the mix).
So, i guess i'm actually leaning against the BYOD idea.