The situation seems to be that (i) the mechanics say that "ray of truth" hurts all creatures, even emotionless ones, and (ii) the players prefers that "ray of truth" play on its target's emotions, and (iii) the player doesn't want to narrate in some further feature of the situation (like weakening an ooze by mocking Juiblex) that would reconcile (ii) with (i).For example, according to RAW, the aforementioned "ray of truth" still hurts the mindless centipede. The mechanics (=eldritch blast affects any creature) calls the shots on the outcome in the fiction (=centipede is damaged). The reverse is not necessarily true: if the eldritch blast is reskinned as a 'ray of truth', and the desired fiction is that the ray of truth will not affect mindless creatures, then the centipede is still damaged anyway according to RAW.
The same thing can happen in AD&D, which permits 2 bow shots per minute, even though many people would prefer a rate of fire closer to mediaeval maximums, and would prefer not to narrate in additional complications (poor lighting, poor weather, etc) that might explain the less-than-optimal rate of fire (whereas Gygax seems to have been happy enough with narrating such additional complications).
In both situations, houseruling therefore seems to be required.
The most natural solution to the AD&D problem is to increase the rate of bowfire (pehaps with rules to slow it down again in bad lighting or inclement weather). Of course, this might produce imbalance with melee. (So shorten the round. Which then might have odd consequences for movement rates - moving anywhere on the battlefield becomes inordinately expensive in terms of attack forgone. Etc.)
The most natural solution to the 4e problem is to make centipedes and other mindless creatures immune to psychic damage (although there are additional complications if the ray in fact did radiant damage, as per LostSoul's later post), or at least to "emotional burdens" damage (which is, in effect, what LostSoul did). As always, this may have balance implications, which I think is why the 4e designers themselves don't do this sort of thing, and (for better or worse) leave it up to houserulings.
For me, this seems to fit well with the distinction between "reading the fiction off the mechanical resolution", and "casually agreeing on the fiction with the mechanical resolution setting parameters for that".THAT is what I was referring to when I wrote "calling the shots" in reply to LostSoul's example.
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Apparently, that made LostSoul's player happy, and I "get" that.
I think this is a pretty big difference of preference. As has probably come out through my posts, though, the main thing that puzzles me about it is why people put up with it for hit points when they hate it anywhere else. I don't get why hit points get such a free ride - not that they don't deserve it (or do deserve it - I mean, it's a mechanic, it doesn't deserve anything) - but why do people who want the mechanics to determine the content of the fiction not got to systems that don't have such a prominent mechanic that thwarts that desire?