The fact that no one used it doesn't mean that building it was a mistake. Maybe the purchase officer got it wrong, but the salesperson who requested it be built got it right, since the deal did in fact depends on it.
In other words, perhaps landing this one client was important to that salesperson, and perhaps in the short term to the company, but in the long term it may have been better to have lost that one deal. Very often these decisions are made with little calculus about the TCO.