Because of perception. You say it's not reality but this game (or any game, for instance) is all about perception. You can break down any mechanic in any game as sets of rules that would be boring by themselves. The way you play, how these rules are implemented and the way you can resolve or fail them is what makes them interesting.
Take that Moonlit/Moonshadowed phase from Tsukiyomi, for example. Fundamentally, it's a DDR mechanic where if you stay on one side of the arena you die, not really different from the basic orange ground AoE that you move away from left to right to avoid getting hit. However, on Tsukuyomi you have much more control over it, and that makes it more interesting.
Of course, you can dislike it. At the end of the day, I can't convince you of anything because I can't make you play with the jobs how they were the old days, for you to see the difference. And that is not even my intention.
I will complain about job designs and battle mechanics because I saw how they declined over the years and want to see the battle system get better like before. I wouldn't be here complaining if I didn't like the game.