Because it wasn't an Enterprise story, it was a TNG story about a decade too late. The main premise wasn't about Archer trying to write a speech and help his friend and the decommissioning of the Enterprise, it's about Riker playing on the holodeck trying to figure out what to do about The Pegasus. The main cast of Enterprise were secondary to Riker and Troi, and that shouldn't have happened in any episode, much less the finale. The best part in the episode was, really, the ending, with the voiceovers of Kirk, Picard, and Archer. That was a proper wrapup.