if you can find a game developer who cares enough to split their game's logic down more than just "render thread" and "logic thread", then maybe an 8core would be useful
Actually the problem isn't developer laziness, it's just common sense. Most games are GPU and/or bandwidth bound, and cpus don't factor in beyond a certain point. Furthermore, if you wake up too many cores, intel cpus slow down so if you do have a monolithic render thread, threading everything else is counterproductive.
DICE is one such developer. BF4 scales pretty well across cores, and so should any game that uses that engine unless crippled artificially. There are other developers as well but most make console only games (Killzone, Uncharted, etc... are all heavily multithreaded).