Also I thought it was one of the better ideas that it is the final stop. And it got even more touching that it was only possible after a time skip. The city itself could still have had more story scenes once you were there. What they could have done for Insomnia though, as Umbra does no literal time travelling but "revisting memories" as it was called, so basically just pseudo-time travelling, that you would have been able to do something in Past Insomnia in one of the final chapters and then in chapter 15 of course as well.