Ethics has its own vocabulary, history, and arguments in ethics are common and often don't have a resolution other than compromise. It's predicated on making logical arguments and has ties to epistemology: how do we know what we know?
So saying you don't understand the point of ethics classes, as if people are ethical or are unethical, is like saying you don't understand the point of teaching logic or debate as if people either pop out of childhood with an innate conformance or resistance to one kind of logic or debate, no other kinds exist and there are no arguments.
If you took an ethics class and don't understand the point of it, then I'd argue it wasn't a good ethics class.