JO was so immersing because it had one complete mission built into the story. Its a bit like the SW films; they show the most memorable parts of what is a very long story. Much like the life of a Jedi wouldn't all be battling Sith and duelling JA shows many different missions that aren't all related.
JO is only a short part of Kyle's life and centers around chasing Desaan and the final battle with Desaan. All the sub plots in JA just made the game feel like you were living a normal, boring life and then at the end you fought a battle. There is no urgency to the earlier levels and they feel like a warm up for the last level, which, in truth, should be a story of eight or so levels chasing tavion around the galaxy. This would add some drama to the game.
I feel a mod coming on...
Sometimes in life you're the pigeon. Other times you're the statue.