pg. 8, the gauntlets were telling him: "this is the last chapter, kiddo".
My uninformed guess is they were aiming to continue the story off the WN, and while they could've continued since there was more material there, a combination of the author going on permanent hiatus/abandoning the WN and finishing what the single volume LN covered, and probably sales, led to just ending it here. Unsatisfying of an end, but enjoyed it up til the trials anyway.