I believe "artificially contrived" is an accurate way of describing encounter powers, in particular focusing on the "imposed arbitrarily" and "forced/planned/strained" parts of the definitions.
They're not arbitrary. There's a reason behind them - namely, the rationing of player resources.
It's true that they ration player resources without a corresponding rationiong of ingame resources, and so in that sense are metagame resources. But so are hit points, at least on the Gygaxian (luck, divine favour) interpretation.
The reason is not to everyone's taste. Nor are (Gygaxian) hit points. But that doesn't make them arbitrary.
As for "forced, planned or strained", they are clearly planned - just like hit points, and much of the rest of the game rules. I personally don't find them forced or strained - I find them elegant. They nicely solve a number of superficially disparate gameplay problems in one fell swoop, namely:
* Reducing the swinginess of combat by limiting the nova-capacity of PCs.
* Encouraging a focus on the situation/scene/encounter as the basic unit of play.
* Reducing the game-breaking consequences of overpowered abilities, by rationing access to them within the confines of a single encounter.
And they do all the above in a way that continues D&D's tradition of mixing it's ingame and meta abilities (like non-meat hit points and pre-3E saving throws) rather than prising them apart into a strictly ingame bit and a strictly meta-bit (HARP and Burning Wheel take this latter approach, and I gather the new version of Runequest does also).
Encounter powers represent an absolute restriction upon an action in the name of simplicity and tying resources to the spine of the game in terms of game balance rather than the campaign world.
I don't disagree with this, although I think the pacing issue is as important as the balance issue.
But the same is true of any number of other features of the game: turn-based initiative and the associated action economy (on which 4e is arguably far more liberal and immersive than 3E, given the widespread availability of encounter and daily out-of-turn actions); BAB increase for all classes in 3E; starting money, and the fact that no PC can start the game as rich as a prince, even though the gameworld is full of princes and princes are notorious protagonists in fantasy fiction; etc. (And there are a number of fantasy games which differe from D&D in one or more of these respects: Rolemaster has continuous initiative, as (to a significant extent) did classic D&D; Rolemaster, RQ, Burning Wheel, etc do not have automatic combat bonuses for all PCs; Burning Wheel PCs can begin the game with the wealth and status of princes; etc.)
All those decisions are made for reasons of pacing, and rationing player resources. Those are pretty important things to have regard to in designing a game.
If simplicity and game balance are important game features for a group's gamestyle, then encounter powers are great. However, if the limit placed upon an "encounter action" is seen as unbelievable and artificially imposed, based upon it being a simplistic kludge (that the previous group would define as elegant) to moderate a character's power level rather than believably represent a more natural (non-artificial) restriction, then as game design it really does not work well for that latter group.
There is nothing "natural" about the action economy or action resolution mechanics in any version of D&D; even Rolemaster and RQ make compromises with nature, but are closer to "natural" in these respects.
But anyway, you are correct that some people (eg me!) see encounter powers as elegant. Hence, describing them as "artificial" and "contrived" is, as I said, contentious.
I just think it is yet another thing that separates two of the major groups of players underneath that one tent. While "artificially contrived" might easily be interpreted pejoratively, it was a succinct (and I believe accurate) way of expressing the idea.
Well, it does present the view of one side of a contentious issue. But I think that tends to affirm my claim that it's a contentious description.
Here is how I would describe the anti-encounter power side: they not only want the game to have rationed player resources (that's part of what makes it a
game), but they object to the "active" part of those resources (like powers) having no correspondence to ingame "active" abilities of the PCs (like, say, a spell known and cast). I think the rationale for these players is that they feel they can only identify with or "inhabit" their PC if their reasoning process, as a player, is a more-or-less strict model of their PC's reasoning within the fiction - and so deciding to expend a metagame "token" like an encounter power violates that sense of "inhabitation".
I think the reason these players tend to give "passive" resources like hit point and saving throws a free pass on their metagame character is because the expenditure of those resources doesn't require a player decision. Note the lack here of a uniform correlation between player and PC: often losing hit points or making a save
will require a decision by the
PC - to duck, to suck the poison from the wound, etc - but the critics of encounter powers don't worry about that. They don't particularly want every PC decision to correspond to a player decision, just vice versa.
So from my point of view, it is actually those who are against encounter powers who are introducing an additional constraint on design, namely, an extra requirement on the mechanical adequacy of a player's active resources. I think it's very hard to design a game that is both satisfying to play and that satisfies that constraint; Runequest and Traveller may be the best two candidates for success here (Rolemaster is perhaps a runner-up). I personally wouldn't put any version of D&D on the list of winners or near-winners. (Part of what I like about 4e is that, from my point of view, it embraces and fully extends and develops those features of D&D that would stop it from winning this prize, by completely abandoning this simulationist constraint on player resources and action resolution mechanics.)
But whichever way D&Dnext goes, I think it is more helpful to look at the actual differences of design preference - eg, in this case (and I think several other cases) the presence or absence of a certain sort of simulationist constraint - than to use phrases like "arbitrary restriction". Particularly because the word "arbitrary", and references to "rules first" vs "story first", are typically used to paint 4e as concerned with delivering a tactical wargame experience rather than a rich RPG story experience. Whereas, for someone with my sensibilities, 4e is just about the only version of D&D capable of delivering a rich RPG story experience, because the only one with the mechanics to do so (such as non-simulationinst player resources on the "active" as well as the "passive" side) without relying on GM railroading.
(And I know some people take the view that the story is whatever emerges from the transcript of play, even if that is "We all went into the caves and got our blood sucked out by stirges. Then we rolled up some new guys, and those guys went to the caves and beat up and robbed some kobolds." When I'm talking about story, I'm talking about something closer to the literary or dramatic notion - characters, situation, complication, resolution, thematic significance etc.)