Using a call button, the flight attendant has to come over twice - once to find out what you want, and then again to bring you the thing you asked for. Any form of remote communication (video chat, text message, whatever) reduces that to a single interaction.

Fewer trips down the aisle, less time spent leaning over other passengers, etc.

If I were the PM on this project I probably would've used a standard menu of services (get a blanket, refill water bottle) in an app on the IFE display instead, but the principle is sound.