I've done the late nighy/early morning "redeye" between ICN and HND, always a 737.
Sure its not a 777 but most of those flights don't feature the apex suites anyway (except NRT-ICN when its a 747 or A330). A case must be made for those old seats on the 737 fleet, they are very comfy especially for such a short flight, they simply don't make them like that anymore.
Fun fact, KE has a fleet of 737s without winglets, something thats pretty rare these days.