Sorry, I replied to the wrong post before.
Some stuff has to do with the engine only with the side view battles and what is visible, mainly to emulate older Fire Emblem games. Stuff like the transitions is like the Fire Emblem games. And Disabling some options in the UI has unintended consequences, but they are mostly there for easy access to those options and to do stuff like save in the middle of battle. Stuff like tree tiles have different kinds of terrain which has it's own bonuses of being in for defense and hit rate.