It's important to note too that the entire program in capacity controlled, so that if a larger number of Platinum and Diamond cruisers book a cruise, they will sell less or no "faster to the fun" passes. And they are saying that Platinum and Diamonds will still get in line first for the other various perks.
I'm not sure I would pay for this either. First, I would want to know the priority embarkation actually means something. My last few cruises, out of Baltimore (Carnival) and Ft Lauderdale (Royal Caribbean terminal 25), the priority only kicked in after you cleared security. Everyone still lined up outside to clear security though. Once inside, the lines all moved steadily and we were on the ship in minutes. I did have to laugh in Baltimore though that the VIP checkin counter was down at the far end of the terminal from where the gangway was, so we ended up ahead of the VIP's who were in line ahead of us. At the Princess terminal at Ft Lauderdale, their Captains Circle entrance is separate from the rest, so you actually do get ahead.