We'll have to agree to disagree on that point. That's not how I was raised...and it's not how I raised my kids...
I generally agree with the idea, but there are plenty of times that I've applied it, and I always end up as the one paying for it. Sometimes, leaving is far and away the best option.
Yeah, I think there are so many people that don't have this mentality today, you have to look at how you're being treated. If the person you're honoring your commitment to has no morals, they just think they're taking advantage of you.
I had a job in college, put in my 2 weeks notice to start a Co-op job in my degree program. I was hired by the owner, who later hired a manager to take care of the business (who incidentally was the type to hang his former athletic participation over your head despite the fact that as a 40 something guy was essentially a McDonald's manager). Manager got ****ed because he was asking me everything to cover the fact that he didn't know what he was doing, so he started riding me publicly over the communication system. One day when the owner was able to listen, and the manager was being especially jerky, I walked out mid shift, probably about a week before my 2 weeks was up.
I called the owner later on that night and apologized for walking out, told him that that's not my character, but I was not going to stand for being treated like that, and if that's what the next week was going to be like, despite the fact that I needed the money, it wasn't worth it. Owner said not to worry, he agreed that the treatment was out of bounds and that he held no ill feelings. He later re-hired me after the manager was gone (not sure if he left or was canned, it happened while I was off on my Co-op).