I'd say it's sometimes ok, sometimes necessary for brevity, and sometimes accurate. Accurate = "All people need oxygen, water, and calories to survive." Brevity = "Generally speaking, people enjoy good food and good company so those situations work well for forming relationships."

Consequences of generalizations have a lot to do with how tolerable they are. If I say, "most people like pizza" there's not much harm if several million people don't. If I say, "all or most people of this gender/ethnicity/religion/whatever have X problem" that's a lot more problematic because it can easily lead to a consequence of harmful prejudice. When it comes to matters of ethics, beliefs, accusations etc. it becomes very important to handle cases individually as much as humanly possible.