Your customer base expects you to do things. They wouldn’t be your customers if not. They expect you to deliver on what you say you can deliver, and they expect you to do it right now. Think about it. You too are a customer and you expect the same thing.
What happens when a company, a campaign, a spouse makes a promise and doesn’t deliver? What happens to the trust? What happens to that relationship?
If Barack Obama promises to ensure that 10% of the nations energy comes from renewable resources by 2012 (he is promising that) and doesn’t deliver, what will voters think of his energy record in 2012 when he is up for re-election?
If Geico promises to save you 15% on car insurance and they end up being more expensive, what happens to their credibility?
If a wife cheats on her husband and he finds out, where will his trust level go?
If an employee is promised a pay increase after 6 months but doesn’t see one until two years, what happens to the credibility of the employer?
Promises delivered create trust which drives sales and delivers brand loyalty. Without that trust, the brand is worthless and the loyalty goes to a competitor. That is never good for business.