There have definitely been unjust wars, where various propaganda has been used to get people to fight for corporate or imperialistic agendas.
Acting like the people that died fighting Nazis, or the people that died prevented North Korea from taking the South, didn't die protecting others is just disrespecting those people. Imagine how many people that have survived, lived, and prospered on the European continent and in South Korea because soldiers and resistance fighters were willing to lay down their life for a greater cause.
This isn't a black-and-white issue.