Yea, Tigers I agree with you on the Johnny/Jack thing. TnT said they were on the Johnny's yacht and he told them Jack wouldn't do something that way and they sort of argued. Maybe this was the argument. POTC is about freedom and the consequences of your actions and IMHO if JD didn't think Jack needed to be with the girl at the end for sake of freedom and "It's not ......but what you can live with" as spoken by Pappy Teague then that was the foreshadowing for Jack to let Lizzy go with Will.
To me, Jack was a minor character in this one. He was not his forceful personality that he was in the prior two. He had his moments, but not many. In the scene with KR he seemed almost to grovel to KR character.
I guess if I hadn't been so reved up for a J/L ending I could have enjoyed the whole movie more. I did like it, but there were points that did not work for me.
Jack showed his love for Lizzy and that he was a good man by sacrificing immortality for Will, and in the scene with the parachute thingy. He even did at the end when he refused the kiss from Lizzy and the look that followed. Only problem is Lizzy never acknowleged him as a good man and that was not right.