So you judge the current people by the action or their ancestors? I ask you again, is extinguishing all life in the galaxy justified by the fact that at some point in the past some dark side users got their *** kicked by some light side users?
the current people? sorry but we are 3k years on the past, the current people would be Sidius and Vader, none of them wished to exterminate all life in the galaxy pal, they just wanted to be the rulers of the galaxy, thing they acomplished.....
u ask me again and i ask u again : starting a war and destroying other people because they don't agree with ur thinking/ way of life, even if they do not interfere directly with u is ok then? as i said generalising the sith society as a whole by what the Emperator alone wishes to acomplish aint correct.
Since it seems u only know about sith traditions from what u see in the game, i will give u a clear example based on the game(s), why does Lord Scourge oposites the emperator and doesn't support his plans? Why does Darth Malgus choses to abandom the empire and Create his own. Why does Revan while being a Darth lord of the Sith followed his own path and tryed to stop the Emperator, why does the spirits of the ancient sith lords were ageinst the emperator and tried to stop him aswell? i recomend u to read a bitt more, before generalising about the sith and their ways...