CP3S said:

Some of its biggest stumbles along the way seems to have been from trying to cater to fans (Jack's tattoo episode, etc.)

Jack's tattoo episode had nothing to do with catering to fans. They wrote that episode because they were spinning their wheels waiting for ABC to allow them a definitive end date. In season 3, you can tell they were dragging their feet because they didn't know if they had 3 more seasons or 6 to tell their story.

Lindelof called up the powers that be at ABC and said, basically, "Look, if you don't let us have an end date to the series, you're going to get more episodes about Jack's tattoo. This show can't go on forever."