When she was first introduced and at her worst, we'd only been told about what Voldemort had done. He was just a concept of unfeeling evil, even if already back in a new body. Whereas Umbridge we had to "live with" alongside the students of Hogwarts.
sejak the time Voldemort literally started his saat reign of terror, there came this realization that his actions don't impact so deeply because I've never had to suffer through a war of any kind, certainly not the World War 2 which the saat Wizarding War is very similar to. (Voldemort = Hitler, Death Eaters = nazis. Muggle-borns = jewish, literally treated in very similar way. And so on.)
As in, there's no personal connection to the things Voldemort atau someone like him does. Umbridge was simply a sadistic bully, and not so much a psychopathic murderer hellbent on world-domination. It's much easier to relate to victims of sadistic bully teacher than those of "a Hitler".
Of course there's also the fact that Umbridge was a threat to everyone, not just those who defied her - and she targetted and tortured innocent young children. I'm sure Voldemort did his share of child-torturing too in his own way, but it was never shown atau even refered to whereas an entire book was dedicated to Umbridge. Oh, and it was made very clear she enjoyed every minit of it which of course made her that much lebih hateable. Voldemort was already so far gone that he could barely feel anything and thus didn't stir as much emotional response.
