Says who? I mean, other than you.
Says everyone with a bit of logic and understanding how body and mind works during and after effort. I don't eat the same thing when I'm running a marathon and recovering from it, for example. And people might incite me to sprint at the end, but I will collapse if it goes on for too long, and it will go the opposite way of my recovery, it will make me stronger for a short while but will make my recovery harder.
Note that I'm on purpose taking a purely physical exercise, because we are talking about martial powers, it's clear that magic can do whatever it wants.
Clearly not the 4e designers - and it was their game that I was playing!
The designers made a simpler choice in 4e (but to me a better one in 5e, clearly separating both). But it certainly means that the game formats the fantasy, whereas I prefer it the other way around.
The half-orc ability you describe - which, as I could said, could equally be given to a barbarian, a fighter or a paladin with no departure from th default fiction of any of those classes (in AD&D cavaliers and sohei both had variations on that ability) - could equally be spend a hit die rather than drop to 1 hp and it wouldn't change the fiction.
And then, I find it really sad that, instead of having abilities which are the signature of an archetype, it gets spread around, like people don't have enough imagination or liberty in the system to imagine something else. And the other classes do not need this in 5e, they indeed have their own ways of dealing with this, between the barbarian's rage, the fighter's second Wind, and the Paladin's Lay on Hands, all iconic and all fitting perfectly their archetype and their power source.
I don't think I've ever been rubbed up the wrong way by "player agency" (which I think means
players playing the game and impacting the shared fiction). But I don't know why you're talking about "erasing player choices". A FitM approach to narrating forced movement doesn't erase anyone's choices - as
@AbdulAlhazred already explained upthread, it's just deferring finalisation of the fiction until all the mechanical effects that contribute to it are resolved.
SInce you don't have a problem with it and it's a vast debate that goes way beyond this thread, I will drop the general subject of player agency.
I'm not 100% sure why it matters, but it's also not true that every instance of forced movement permits a defence. Just looking through the "D"s in Monster Vault, I found that the Savage Displacer Beast can push any enemy who misses with a melee attack, as a free action at will and no attack roll required (it's an effect). The Displacer Beast Pack Lord has a limited use attack called Clear the Path which slides on a hit (3 squares) or miss (1 square). The Doppelganger Infiltrator has an ability called Perfect Replica, which is an effect with no attack roll required and that immobilises its target; and it has an at-will opportunity action Replica Switch which permits it to swap places with an enemy affected by Perfect Replica if they are adjacent and a third party makes a melee or ranged attack against it.
And for me, this is bad game design, having abilities which have an automatic effect without any defense, especially a bad effect like this, which means that whatever you do to target, you will choose wrong, and this works on anyone in the world ? There is no justification for this, whether in terms of game design or in terms of player fun, it's only a technical gamemaster's tool to punish the player without giving them any chance. Bad design.
And a couple of final points about forced movement: in the fiction, Horrific Visage is nothing like Thunderwave. The latter is a blast of energy. The former is what it says on the tin: a horrific visage. The reason the character moves is because they recoil in horror (it's a fear effect). I can imagine contexts in which the most apposite narration would be not that the character recoiled at all, but that they never approached - eg if the ability was used as an immediate reaction after having been readied in response to a character moving towards the Wight.
Only it does not work that way, it also does damage (and again, why) ? And it also affects a zone, so why would that character be affected that way ? And what about remaining movement for the character ? Honestly, I find it significant that you play an edition which is so formal about rules and movement and constraints and, in the end, ignore the way it is structured because it gets in the way of your narration, others example below. You ignore the 4e rules like dying or movement or triggers or effects when it suits you (which is fine) but at the same time you have a very technical game (see the examples where the number of squares are justified to a great level of detail).
It's good that you find your fun that way, but for me it's much easier to be freeform (if it's what you are looking for) in a game that is much less formal to start with, that's all.
That wouldn't negate any player agency.
It sort of does, what happens to his choices of movement ? before and after the effect, for example ?
Another, similar example: an Elder Green Dragon has an ability called Luring Glare which slides a target that is hit with an attack against Will; and it has an at-will immediate reaction, Cunning Glance, triggered by an enemy shifting to a nearby square, which permits the use of Luring Glare against that enemy. It would be very natural to narrate the effect of Cunning Glance as the enemy never moving, or moving directly to where they end up, rather than first assuming that the character shifts and then that they move elsewhere.
You can describe it whatever way you like, but still it's another example of pure technical design. Why is this triggered by someone specifically shifting ? And not simply moving ? And why does a charm just move a target ? It's all bizarre and technical and justified backward from the technicalities of a power invented to technically surprise someone.
Here is the actual play report:
I regard this as perfectly representative of how 4e plays. Of course at lower tiers the fiction was different - at Heroic there were boats and Goblin warrens and tombs; at Paragon there were hobgoblin phalanxes and Underdark caverns; at Epic the PCs fought demons and destroyed Torog's Soul Abattoir, as well as assaulting the Glacial Rift of the Frost Giant Jarl.
Oh my god, it is so technical. But still with you ignoring rules when you feel like it. As mentioned above, I have found that playing freeform and story-oriented works better with a lighter more free-form game, but it seems that it's not only that, you also enjoy extremely tactical gaming, while at the same time your players seem to roll in with arbitrary decisions by the DM.
I ran a very large number of skill challenges in which the Arcana skill figured, and magical effects were dealt with. The character of those effects as magical was a matter of fiction. Not a mechanical concept. (Almost no non-PC-generated effect has a power source; rituals do not have power sources; and in any event power source is a keyword and so its presence in the rule you quote is redundant. In our game we focused on the fiction.)
So one possibility is that you played the game correctly - ie having a bad time - and I mis-played the game - and had a good time. Another is that you misunderstood the game, and as a result had a bad time, and I worked out how the game is meant to be played, and had a good time. Which you think is up to you. I know which I think.
No, I'm sorry, but multiple examples show that, technically, you player the game incorrectly. However, practically, you played the game right, because you were having fun. As for ourselves, we tried to play the game as designed, so technically we were right, and simply did not have as much fun with it as we had with other editions, and, frankly, 4e is not suited to modifications on the fly, if you start unraveling a principle, you end up with more questions than where you started. But it's good if your players and yourself have an agreement about this.
But I still disagree that this is the way the game is meant to be played. AFAIK, there's no section about simple ad hoc rulings, it's all about the formal rules from beginning to end, and designing house rules is extremely formal, and it even challenges you about why you want to make the change to the core rules. And it needs to be written down. It is the most formal edition of the game ever.
How to be a Dungeon Masters starts with "A competitive sport has referees. It needs them. Someone impartial involved in the game needs to make sure everyone’s playing by the rules." That section is all about the rules. Compare to 5e: "A Dungeon Master gets to wear many hats. As the architect of a campaign, the DM creates adventures by placing monsters, traps, and treasures for the other
players' characters (the adventurers) to discover. As a storyteller, the DM helps the other players visualize what's happening around them, improvising when the adventurers do something or go somewhere unexpected. As an actor, the DM plays the roles of the monsters and supporting characters, breathing life into them. And as a referee, the DM interprets the rules and decides when to abide by them and when to change them."
The role of referee comes last, and it's all about interpretation, deciding to abide and change them. Totally different philosophies here (and again, I'm not judging the quality of that, just the intended design and what it means for the types of game best suited to an edition).