Promises are made for several reasons and because of this, a "promise" and the importance of such a thing means different things to different people.
Someone who makes a genuine promise has the full intent to keep it and will do almost everything and anything in their power to do so. Maybe even sacrificing their life or their own happiness to fulfill that promise.
A promise made for selfish reasons or personal interest is almost always broken. The promise that you make, whatever it may be, should be made for selfless reasons. If you only think about yourself and not the other person, in the end you won't be able to keep that promise. Even if it is a promise made to yourself, say to reach your goals or to find happiness for yourself, if you go about it without thinking about others around you and those that will be affected by your decisions, your promise will never be kept. And if you do end up keeping that promise to yourself, is it really worth the cost? Regardless of whether or not you think so, all promises come with a price, both good and bad.
Unfortunately promises are made and broken everyday. Ideals and morals are either formed or compromised in breaking a promise. The same thing could also happen in keeping a promise. To me, a promise is like a false sense of hope. Why make a promise if you don't intend to keep it? Even if it wasn't your intent to break it, nothing hurts more than genuine words taken back.
Don't get me wrong, I make promises all the time, ones I keep and ones I can't. In that sense, I am a true hypocrite. But in my defense, I only write this because I feel that it is true. Promises and the importance of a promise really does mean different things to different people.