Sometimes that is a business need, but the rest of the business doesn't recognize it (or won't until it's too late). Yes, having your website running on coldfusion 5 isn't actually a problem - data comes in, data goes out, orders are filled (ecommerce, for example). If the actual business needs didn't change ever... there would not be a need to ever refactor/rebuild.
And yes, I've seen "needless" refactoring, without regard for business needs. But there are folks who do understand some of the needs of the business before the other business units may realize it themselves.