Enjoying the death of an entire group of ficitional people?

[Akkleptos]

As long as the group of people are fictional, feel free to rejoice at their deaths. Writers and game developers create villains for a reason. That's all.

Unless you were playing, say, a game in which at some point you learn that the current enemy happens to be on the good side, and your current objectives were all the wrong ones (e. g. Chrono Cross).