Whether you've taken this route or gone in the opposite direction, there are two basic scenarios in the decision-making process.
Scenario 1: Someone comes up with an idea that might better serve your customers. But it's different, and a small but influential group of senior staff shuts it down because it would change things, or because one of them knows this great vendor that could do it better and they can "prove it."
Scenario 2: Someone's new idea becomes "the fad," and suddenly you're implementing a product that half the staff knows is not the best solution. But no one stands up and says, "Prove it."
I have seen ridiculous TCO numbers concocted just to support a predetermined conclusion that matched preconceived notions.