Completely agreed. People will remember you. What you can do and get away with legally or even ethically is not always what's best for your future.
It's a bad idea to tell to your boss why you're quitting, and it's a bad idea to quit without giving your boss and coworkers notice so they can make plans to handle the mess you leave behind as easily as possible.
Likewise, employers should do what's best for word-of-mouth, too. They might have every legal right to terminate without notice, and they might even feel it's ethical to do so for various reasons, but ex-employees will talk, and current employees are paying attention too.
There are always exceptions, when quoting immediately or firing immediately is called for. Those situations should be obvious to everyone.
We must believe that it is the darkest before the dawn of a beautiful new world. We will see it when we believe it. -- Saul Alinsky