Have you thought about how nice it feels to hit a good Iron shot? And then to do it again on the next hole?

It’s more than the scorecard. It’s more than the improving handicap. It’s a real feeling of pleasure and joy to hit good golf shots.

There have been many, many independent studies completed on the link between club fitting, performance, and enjoyment.
Golf.com published one recently that had some very interesting examples, including this one for a set of Irons: