You are 100% correct. Evey is pretty much taken advantage of by V. And the reason is because she is meant to symbolize the downtrodden English public and was not created as a decent character in and of herself. More evidence of how this is such a bad movie. Frankly, I never quite understood why there needed to be an Evey character to begin with.

(Though I'm not a fan of graphic novels, I read this one. While I may not have really liked it, at least I was able to appreciate that it gave a much better explanation for why Evey was in the story.)

You know what I didn't like about Evey other than her personality (or lackthereof)? Her wardrobe. When all the other clothing in the movie was either slick and smooth or rumpled to fit perfectly with the character, her wardrobe looked like it was designed for some other movie, possibly involving freaks and geeks or Napoleon Dynamite.