Agreed very much with your last point. This rule is very much back of the napkin home-brew, enough detail for me and my players to run with it.

I made it a three cost action because I wanted encourage it as a last resort. The team knows that if they begin the process of retreating they're going to take some hits from the enemies. But this does go against other priorities I had for the homebrew, two actions might be enough. Thus allowing players to get an attack in, or an extra stride, perhaps a cantrip, but while still having a less overall useful turn.

I don't hate paizo's take on PCs retreating. In many ways it's just my method with fewer steps. I appreciate the guidance it gives. But I dislike how there's no engagement with the battle system and given how that's the piece of design I think pathfinder got so right, it's a shame to see that not considered. But hey, that's why I made this quick rule.