I have been told all my life to be "nice." This, of course, is something women get told all the time, but I've experienced it, too.
Being "nice" is something that isn't valued on the internet. The phrase "Well-Behaved Women Rarely Make History" is used a lot, although interestingly the original usage was decrying the dichotomy that makes women either "nice" or "aggressive," a sort of variation on the virgin/slut dichotomy: http://www.hamilton.edu/news/story/wel… (and of course, inevitably it's been attributed to Marilyn Monroe. Sigh)
My problem with this is that the focus is put on the "bad" behavior rather than the reasons for it. The women (and men) who change things don't break rules just for the hell of it; they did so because the rules contradicted one of their higher beliefs or principles. (That's why I also hate the "here's to the crazy ones" nonsense peddled by Apple.) In other words "good" or "bad" behavior only tells half the story (otherwise Lindsay Lohan would be an example of someone who "made history.")
But back to "being nice." My problem is that often "being nice" is confused with being kind. Kindness should be encouraged. It has little to do with tact or rules. Being nice means holding your tongue when someone is a jerk. Being kind is letting someone know they're being a jerk in the gentlest possible way. There are plenty of reasons not to be nice; there are no reasons not to be kind.