The end for now with the 13th isn't actually a bad result, it resolved the issues, introduced key elements and plot points (the scales, domains, the memoriate and the cause of the 13th's fall in the first place), it potentially sets up a new role for the 1st in the future, doesn't rule out a void expansion in the future even. It's an intermission chapter that works well enough.
All in all it does what it needs to do, lay the ground work for something good later on if they so choose to expand upon it and it lays some key ground work for cross rift travel that may eventually lead to expansions on one of the other shards down the line. Those elements might not seem much now but they build off existing lore and set the stage for the future of the game.