JFK-KEF is blocked at 5.5 hours which means it's closer to 5 hours of actual flying time. Why would you overshoot Iceland by 1200 miles, make a connection and then double back 1200 miles for a lounge and lie flat seat when you can be there in 5 hours direct?? I get the loyalty to OW, but sometimes it's just not a fit for the trip.
I definitely get the reason/benefits of doing the non-stop, and I still may book that. I was just looking to see if there is a way to ticket the Oneworld option on a single ticket instead of as separate tickets. I like knowing all my options :-).