Sounds to me like the perfect solution would be to allow EasyCheckIn Online or at a Kiosk while travelling with baggage, and have a separate baggage drop zone where your bag gets tagged. That way, all those complicated seat change and counter transactions happen online or at least at a Kiosk, and the only step left is to drop off your bag.

This can be done at a Skycap, but maybe there needs to be a more formal solution at all major airports.