I understand that exploits are not explicitly metagame. In this way I think of them as like hit points - depending on one's take, they are either flexible or incoherent!
But what I'm missing, I think, is why you think they can't be treated as metagame. In what way do they not affect metagame things only? Maybe there are some rogue powers that I should have in mind but am forgetting about (I'm not really up on my 4e rogue knowledge), but for fighters they're basically more attacks, more damage and more knockback/down, and for rangers they're basically more attacks, more damage and more movement.
The damage boosts and knockback/down strike me as bascially dice manipulation - analogous to using an explicitly metagame option to reroll or boost damage dice - and the additional attacks seem to me basically to be manipulations of the action economy, which as I've said seems to be obviously metagame (because of it's stop motion implications if treated otherwise).
There are some exploits that you can easily treat as purely metagame in effect; any +X attack or +X[W] damage or similar purely numerical manipulation effects are easily explained that way. Your continuous action example bear this out well: the difference between getting a lucky crit on one attack and using a +2[W] power or between hitting with both Twin Strike attacks and missing all but two Sweeping Blow attacks isn't all that noticeable, and as someone noted earlier having multiple similar powers can hide this effect. But when you get past pure numbers and get to things like pushing or stunning or moving more than your speed or hitting everything in reach, the disconnect between the fiction ("here's stuff you can do") and the mechanics ("...but only once per day") is irritating.
Making enemies attack themselves (Bloody Path, Rogue 15), becoming invisible or just hiding amazingly (Hide in Plain Sight, Rogue 16), getting free attacks against people who attack your allies (Strike of the Watchful Guard, Fighter 19), immobilizing someone (Dizzying Blow, Fighter 5), and similar are all things that martial characters can do that can't just be treated as metagame things without some serious inconsistencies. The rogue can hide so perfectly that he can remain unseen in broad daylight in the middle of an open field...until he moves, then he can't do that again for a day? The fighter can pick one enemy and take advantage of every opening...but can't do that to anyone else that day?
Anything with that kind of obvious observable effect, with those kinds of obvious tactical advantages, are things that characters would notice and try to take advantage of--if I were a rogue and could turn invisible if I didn't move, I'd use it all the time to sneak in somewhere, wait until a guard left, move to the next room, wait until the guard left, etc.--yet they just can't use their abilities for no obvious, satisfactory (to me, at least) explainable reason. If you can hide
that well, why only some of the time? If you can guard someone
that well, why only some of the time? If there were some sort of in-game limitation without such an arbitrary usage restriction such as "need to Bluff to HiPS, -10 penalty per use against someone who just saw you do it," or if there were some sort of metagame counter to the metagame restrictions (daily exploits are usable 1/day, spend an action point to re-use), they would be more palatable, but as it stands the contrast between the character being able to go all day on pure grit and adrenaline doing awesome stuff by the fiction and the character being able to pull off awesome tricks only on a per-day basis by the mechanics is jarring.
I don't think I get this either. Why do encounters and dailies as metagame stop named martial manoeuvres? In the fiction, the fighter PC performs "Whirlwind Attack" - but on some occasions, its mechanical impact is limited to one target. (Or, if that seems too much trouble and/or too inane, the fighter player can use Passing Attack, say, as one manifestation of his/her PC's Whirlwind Attack, although if there are 3 or more adjacent enemies it will only ever hit two of them.)
The named vs. unnamed maneuvers point was in response to the earlier assertion by several people that you're not actually doing a specific thing in-game, you're just "fighting" and the exploits are what happens when you do. If your fighter has a Parting the Silk maneuver that he talks about, you'd expect that that maneuver
does something particular in the fiction. It's kind of disingenuous to say "Oh, I use Parting the Silk a lot, it's just that I only hit with it very rarely" to justify a daily usage of the maneuver. Yes, it makes sense that harder maneuvers are less likely to succeed, but if you tell a player "You can try X a lot but it isn't likely to work often," he'd probably expect a mounting-penalty system or a random-opening system, not a hard cap that he has to work around to justify things in-game.
I disagree that the warblade does it in practice any better than the AEDU fighter. But tastes vary.
The recharge, and by extension being able to pick the right maneuver for the situation, is the key point. Use a maneuver once, you can do it again. Have a maneuver that works well against highly mobile foes or larger foes or very damaged foes, you can keep using it. "I know how to do X, so whenever a situation comes up where X is useful, I can do X" makes much more sense, and is more useful in play, than "I know how to do X, but it'll only work once."
This. You're pushing hard at one edge case for AEDU from my perspective. It's not wholly meta and not wholly IC - but a decent compromise.
I don't think it's an edge case. The example you quoted, of 3e Diplomacy not making sense in game, is a believability issue many times it's used, not just once in a blue moon. Likewise, the issues with martial dailies doesn't come up every single time my group plays 4e and a martial character uses a daily power, but it comes up enough to be a big sticking point for us.
An AoO-spec fighter in 3e, and presumably a Slayer in 4e, can use everything he has on any attack, whether a normal attack or an AoO, and sometimes even has extra benefits on an AoO. So getting 2 AoOs is essentially the same as having 2 more attacks on your turn (with the exception that they're triggered, of course; "I can definitely kill all 4" and "I can definitely kill 2, then I can kill the others if I'm positioned right" have different tactical implications).
