You're wrong, it was awesome.
It was pretty damn good. Sorry that Jaburg can't understand what happened even though Jack's dad explained it about as clear as anyone could short of pop up video titles.
Jack died.
His father explained that everyone there was dead but that they had lived for, sometimes, years or decades after the events of the island. The whole Christian Shephard telling you straight up--"It's all real. Some died before you, some died long after you" i.e. (Boone, Shannon, Sun, Jin, etc) and then Hurley, Kate, Sawyer, Desmond, Ben, etc. The island was the reality, the flash sideways was whatever you want to call it--Heaven, purgatory, after life. Everyone eventually ended up there because there is no recognition of time.
(Case in point: Kate missed Jack [implying they'd been apart for years]; Hurley told Ben he was an awesome sidekick [implying they'd been guarding the island for years after that]).
Ben wasn't dead yet because, like Richard before him, he wasn't aging. So he stayed outside.
