[quote=Masaki Haruna]
What's with everyone being weak to genjutsu?
[/quote]

I'm fine with that. It means I can cover them all with my sensory ninja. 

Besides, people don't use genjutsu because... It's an autohitting thing. You can't effectively block it, and the only way to actually provide any interesting battle would require the victim of the genjutsu to powerplay out of it. It's not fun to fight a genjutsu user, and it's not fun to play as one.