Many did including myself. Torial is so vague to get past first try without killing her that it's pretty much intended for the players first playthrough to be a neutral ending. After that, the game pretty much tells you at the end how you should maybe want to play if you want a happier ending.
It's also worth noting the encounters are more than just kill/don't kill. The amount of interactions some enemies have is great. You can upset quite a number of them without actually killing them, for example. On my very first play, I'd disabled the yellow/pink Spare text (not knowing/caring of it's importance) so I had no idea if I'd made the monster happy or not. This resulted in kills more out of frustration, but also a lot of experimentation in the encounters. An amazing first playthrough.
Edit: I mean, think about it, playing the game as if it's just another retro JRPG is just what the game intends you to think. It's also why it tries so hard with Torial at the beginning to invoke feeling bad if you kill her.