Despite the fact that everyone idolizes her, keep in mind that she NEVER thought herself worthy of all that admiration. If there's one character who didn't have faith in Relena, it was Relena herself. It's the reason she recognized the peril her kingdom was in. She referred to "a peace as fragile as glass," after all.
As for being judgmental, Omnicat has said this way better than I ever could:
Her idealism doesn't spring from naïvety, but from pure, undiluted stubbornness. She wants to see right to be done, and won't take no for an answer. Simple as that.
Relena does what is right. Not what is easy, or safe, or practical, or good for her. What is right. No compromises. She's willing to make sacrifices, take risks, make a fool of herself, do whatever is necessary for what she believes in. Even when she knows that what she wants is as good as impossible, she gives it her all. Just because it's hard doesn't mean it's not worth it.
Source:
http://omnicat.livejournal.com/123371.html
Everyone thinks the pilots are awesome because they fight and so on. Relena sucks. She's the one trying to stop the killing, trying to make people see sense. She's a buzzkill for the action. However, these teenage boys live in a world that forces them into becoming murderers. She has to be "judgy" and voice her opinions to change that world. In what way is that wrong?
And I resent that comparison to Lacus. Relena never had to give Heero a Gundam, run a ship or be a fucking pop star to make her mark.