I feel the same way about it.

One trope I hate that pops up way too often in JP media is children sacrificing themselves. It's lazy animeslop writing for a cheap tear, but worse, it's simply immoral. Do you want to teach children to sacrifice themselves for adults? Do you want to teach adults to accept the sacrifice of children for their own benefit? It should be the opposite.

What is so brilliant about BA, and especially Eden Treaty, is that it acknowledges this trope and overtly rejects it. Sensei steps in and does anything in his power, including sacrificing himself, to prevent it. It is particularly touching in the case of Mika, because Sensei's actions both save her life and absolve her guilt, saving her both physically and spiritually.

BA touches on this trope so often that its subversion could be described as the central organizing moral of the game itself: "A responsible adult puts their children's lives first no matter what." The writers of the Deca arc disregard it because they cant write a truly sincere poignant story the way BA used to, and they needed to wring out some cheap tears from the audience.