Why doesn't the action button have more functionality?

I think it was a total oversight to not let the action button do more than one thing at the same time. For example, customizing a long press to do something different than a double tap, triple tap, and quick press simultaneously. If you want to get more customizable, they can even make it so a custom sequence of presses and holds can trigger different things, but that might be too much. I know Apple's whole thing is simplicity, but I hate to see simplicity kill functionality. I mean even back tap allows double tap and triple tap to do 2 things simultaneously. The action button should at least be more functional than double tap.

What do you guys think about this?

(For the record I don't have the iPhone 15 pro yet, but I've used it and quickly realized that this should totally be a feature)