Can't agree more. We have built some internal applications where everything was implemented, the acceptance criterias were met and everyone was satisfied until they actually started using the system and said, ".. wait a minute, this doesnt help us as much as we had liked". But, we had already moved on to the next big thing.

"If I’d asked people what they wanted, they would have asked for a faster horse" - Henry Ford, http://bit.ly/kmLhvZ