Well if you ask me, they couldn't really have ended it better.
It's like the other life they were showing while on the island was their "purgatory" life, and they all died yet at different times, and could not move on until everyone was dead. That's why they kept with the fact they all had to be together to go back to the island, or to try and leave. Once they all had died, they met up and were through their purgatory, time to move on.
Except for Ben, cause he was a ******** rat and didn't deserve to move on with them. ^_^