I'm betting they just have a harder time with xbox updates, so the ETA for xbox is just that much more inaccurate.
And.. I'm pretty sure they know there are going to be bugs with each update, but I can understand where they don't want to release it while there are bugs that are obvious or major or will make people more irritated than not having the update release "on time" (the eta).
wishful thinking: i really hope the internet doesn't tell us the 10 min. shortcut to unraveling the mystery before my server even gets the update installed.
fly here, then fly here, then fly here, yey you beat the game..