I doubt that seeing your mother plummet to her death would put you in the most stable mindset. All you know is that a man came to you, gave your mom a weapon, and led her away to certain death. Same reason why a wife might hate the army if her husband died in service, even if he had volunteered. It's not that it is Snow's fault, but he is directly responsible for her death.

And either way, Hope does admit that he was using his hate for Snow as a coping mechanism for his grief. This honestly makes his character arc the most realistic the series has ever had, in that that's very much how a normal teenager would react in the situation.

Oh, and by the way, I'm ALL for a Lightning-hate club. She became my least favorite between the time she beat up Sazh and punched Snow, two MUCH better characters than her. And she doesn't even have a reason for whining so much, as everything that happened the way it did was basically her fault for being a bitch.