I think the reason NA struggles is because we had no incentive to stay ahead, and we got too much money too quick.
NA was the first to get real money, and sure EU caught up fast, and even won S1 (edit: I fat fingered and hit the number 2) worlds, but they never made the same money, especially with streaming, because most of the players aren't marketable.
China came in without all the money and it came naturally, now they get the big bucks to just buy the good players to add to their pool. Then again they have about 5 bazillion more people to pull from realistically.
I just believe it all comes down to money, and pro players lose the drive (even if they won't admit it) when they see the big bucks.
While Everyone has a drive to succeed, when you are making as much money as some of the NA players do just from streaming alone, it is probably hard to see the old goal when you have cash and seem successful in other ways.
Of course there is also the NA factor that other regions don't really have. If you take Doublelift as an example, he has interviews, streaming, sponsor events, team sponsor events, etc etc.
Korean players, say, Faker (not comparing the two players in skill just in recognition). Faker doesn't stream all that much unless he is doing solo queue for practice, he doesn't go do his own sponsorship thing, etc etc. He has a strict schedule of practice and play that most NA players take advantage of and choose to relax or play...counter strike or hearth stone (like most of CLG has gone on record of saying they play as much cs:go the past year as they do practicing solo queue)
It all comes down to money. When you get the money, you feel accomplished, when you aren't getting paid UNTIL you meet your goal, you have to be more highly motivated to succeed.