Do you think it's fair to include the previous gen consoles with their giant somewhat stagnant install bases in those calculations as they are obviously bringing down the average attach rate. If you look at just PS4 in NA versus WiiU in NA you see that WD sold 968,000 on an install base of 3.4m (about a 30% attach rate*) while MK8 sold 480,000 (about a 20% attach rate*) on 2.5M. That paints a completely different picture to the attach rates you put in the OP but they are equally correct.
*math is done in my head and therefore almost certainly wrong to some degree.
I guess I was trying to prove that cross gen titles shouldn't exist
But you're right, I'll change the OP a bit.