I don't see the metagaming critique against showing greyed-out options in dialogue. Sure, I could see that a check requires Persuasion and reload before it to put points in the skill. But then in the next dialogue where there's a skill-gated option that is not Persuasion, I can't do that, because my points have been commited already. It is still a character choice that I've made that excludes other options. Showing unavailable possibilities isn't akin to a quest compass or even a cheat, it just tells you the options the GM will allow in specific encounters, since the GM isn't super adaptable unlike in PnP.
There are two cases where it could lead to metagaming. The first is if there's only one skill ever used in dialogues, so putting points in the say Speech skill is like having a win button for dialogue. But still, in that case, points in Speech will mean less points in other things, so it's a meaningful character choice that blocks off other options. The second is if skill difficulties are low, and you're able to pass all or most checks in the game just by knowing what checks happen when and what skill levels are required. But that's just bad RPG design. The fact that greyed-out options are shown is not to blame for such a shit design where you can be a master at everything.
So what's actually the problem of showing unavailable options?
Quantomas talks about "texture" and "experience" becoming less "rich". But really what specifically is lost by exposing possible options to the player? And what is gained by hiding them?
One thing is obviously lost by hiding options: the game obfuscates possibilities of interaction from the player, and players can't adapt to how skills are used in this game, see their relevance, their reach, or their impact. A player would have to reload and choose something else to notice the difference. To some, especially if it's hidden that unlocked options are skill-dependant (no [Intelligence] tags for example), it might not even look like there is C&C / alternate choices. One thing is for sure, players won't know the extent of the possible branching because the options are hidden.
One argument for hiding options a player can't choose is immersion; maybe that's what
Quantomas is saying. But I feel that's really a matter of preference. I don't feel a loss of immersion if all options are exposed. The opposite, in fact. In knowing that there are other options, I know that my choice matters and makes a difference, if the game's well designed with good C&C for different choices. It also feeds into my fondness for system thinkering, game design etc.
A second argument for not having greyed-out options is player creativity, the possibility for players "to figure out a successful strategy on their own", like
Fairfax says. A player can feel clever of unlocking an option by thinking about it beforehand and allocating skills / getting items / doing things to do so. That, I feel, is a better argument. I'm all for it in PnP games. But cRPGs are very limited in the options they provide, and so most of the time creative strategies aren't even implemented, and if they are they aren't systematic at all. Plus, if a lot of the figuring out is simply how much skill points to allocate to a skill, that's pretty terrible as an expression of player creativity to deal with a situation. But if the game truly embraces creative strategies on the part of the player, then sure, something might be lost if those strategies are immediatly exposed on starting a conversation.
A possible solution to this issue would be to partially show greyed-out options: that there is something skill-, item- or action-dependant, but not what it is. For example, [Persuasion option], [Item-dependant option], [Previous choice dependant option], etc., without the dialogue line that goes with it. That might be a good compromise, informing the player of existing options, but still requiring some figuring out.