A promised feature feels like something you already have, and just need to wait for a little bit. But your plans can change. Maybe you change your priorities,

A promised feature feels like something you already have, and just need to wait for a little bit. But your plans can change. Maybe you change your priorities, maybe you discover that a feature is harder to implement than what you tought and you must reduce its scope. Or maybe you realize it was a bad idea after all and decide to implement a different feature. If you have promise the original feature, instead of happy users for the improvement, some of them will be angry because of what you "took from them". That's why I think the real politeness is to never promise nothing concrete until you are actually ready to ship it.