I don't understand their rationale for the big divide between D+ and Pinnacle. And, like you say the perks are not really worth the trouble to attain Pinnacle unless you are close to it.
I read the other day that "Super Mario" just finished his 500th cruise with RCI. He is Pinnacle Member level. But then he can go aboard Liberty Of The Seas and stay there for months at a time, racking up points.