I care because I might be working in this field sometime in the near future. I don't just need money for food, clothes, bills, and shelter. I need it for video games and dvds and stuff (and me pirating would just be counter-intuitive).
As Extra Credits pointed out, even if you claim you wouldn't have bought it anyway, the fact that you pirated the game means that it IS worth playing. So either buy the game you think you will dislike but want to play anyway out of morbid curiosity (or whatever) or save your time, money, and mental health and just don't play it.
You may not like the company or the game, but the fact is that all those programmers, animators, etc. worked as best they could on it under the circumstances. Even if they agree with your opinion of the game, the fact is that they're working on it because they need the paycheck and experience, and it might even be their ticket to working on a better game. Putting your all into a project you think is stupid or like is a good job quality in this field. When people hire, they look at the work, not the storyline. (Unless you're the writer, in which case, yeah they will look at the storyline.)