I think it's less all that and more that it's been developed for PS3/Xbox 360/PC/PS4/XBOXone, while Killzone has been developed from the ground up with only PS4 in mind. That said, without sounding like the broken records on this thread, I can't see why anyone would buy these cross platform games on a console, if they have an even remotely decent PC.No shit.
Think about it.
Battlefield - 64 players; Killzone - 24 players
Battlefield - tons of destruction and 'levelution'; Killzone - limited destuiction
Battlefield - huge maps that sprawl for miles; Killzone - small corridor maps
Battlefield - tons of vehicles; Killzone - nope.
Battlefield - 60fps; Killzone - 30fps