Imagine trying to explain life in New York City to members of an undiscovered tribe in a rain forest. Now try to imagine understanding a society that is much more advanced than ours. Our imagination is limited by what we know.
Are the designers that make aliens for television uncreative, or are they working under constraints that we don't understand? Part of the answer has to do with the nature of television production, but the other part has to do with you.
People will often attribute minds and mental states to things that aren't people. It seems silly to believe that storms actually are angry, but what about when we attribute something like jealousy to a dog?