Have you ever thought that Japanese manga doesn't seem quite right when translated into English? I mean, the story is the same, but there are subtle differences that affect the "feel" of certain scenes. Like when a female character refers to herself using a word only men would use for instance. (In Japan, there are several ways to say "I". "Ore" and "Boku" are used mainly by men while "Atashi" is used by women only.) The English language simply cannot convey these minute variations and would probably consider it as discrimination.
Another thing that gets lost in translation is the level of formality used in conversations between people of different social standings. (The Japanese use different words when addressing someone of superior rank than when they are talking to a colleague or subordinate.) There are also manga that contain cultural idiosyncrasies that a non-Japanese person would simply not understand. And then there are the word plays that just don't make sense when translated into another language. Trying to resolve this issue, some manga have side notes that explain things that were lost in translation, and others modify the context a little and make it more Western-friendly.
I guess that's why there are a lot of people who say that the only way to fully appreciate Japanese manga is to read it in its original Japanese form. But since I don't know how to read Japanese yet, I will enjoy reading the English translations and not complain too much. :)