I've certainly read much about the plain imperative being very rude and almost insulting, but I also happen to hear it quite a bit in day to day usage. Espically 'miro' for some reason. I hear it a lot in movies in context that are not at all meant to be abrupt, and I hear it on the street a lot between people jsut pointing things out to each other. The most recent was at the zoo the other day a woman was telling her kid to look at the kaba, and she used miro. Not in a scolding kid of way, but in a 'wow, look at that' kind of way.
How is this normally used?