I like playing monk characters, and the idea of using Punishing Kick to kick someone off a cliff, or into a pit, or through a Wall of Fire, etc., is awesome. Unfortunately, none of those things will ever happen, insofar as the feat text provides that "the target must end this move in a safe space it can stand in".
Not only does this rule prevent all the cool things one might like to do with Punishing Kick, but it makes no sense in the context of the game. I'm willing to suspend disbelief to believe in dragons, in magic, etc., but I have no idea why this feat will only let me kick the target into a safe space.
Questions spring to mind. Can a character use the feat to kick someone into a pit if the target doesn't know it's there? What if the character doesn't know it's there either? Does the Universe simply disallow movement into unsafe areas even if neither combatant is aware of the danger? Could I test for traps by using this kick to push fellow characters across the dungeon floor (either with nonlethal damage or a good quantity of healing) and then note which squares they can't enter?
I am sure that the rule has to do with game balancing since, as written, the feat allows a Fortitude save, but only against being knocked prone and not against the knockback. In order to allow the feat to be used as it should be, I would think that the Fortitude save should apply both to the knockback and to being knocked prone. That way, the target isn't disadvantaged (since the feat requires both a hit, and permits a save) while still allowing the feat to be used to its full potential.
As an aside, I don't understand why Improved Ki Throw exists. Shouldn't Ki Throw permit the same effect? From a common-sense perspective, what is different about throwing someone into an unoccupied square or an occupied square? It's the same throw in each case, right? Why, then, does my character need a new feat to do that?
All comments welcome :)