I agree with your premise, and yet I find your specific example flawed. If Martin took inspiration from a historical time period, making the language sound like it could come form that time period is necessary for the setting to feel like an actual world. It helps to establish tone and internal consistency while subtly divorcing it from reality, all of which helps build immersion. If all his characters spoke in modern language ("hey man, let's grab some breakfast and chat about who's gonna deal with these ice zombies,") you can bet that his world would not feel the way it does.
Obviously, you can also take this too far the other way by doing things like having a made up term for every other noun even when it would work to just say the normal word, but if your fictional world is loosely inspired by a certain time period, making sure that reflects in your setting's language is good writing, not bad.
I agree with your premise, and yet I find your specific example flawed. If Martin took inspiration from a historical time period, making the language sound like it could come form that time period is necessary for the setting to feel like an actual world. It helps to establish tone and internal consistency while subtly divorcing it from reality, all of which helps build immersion. If all his characters spoke in modern language ("hey man, let's grab some breakfast and chat about who's gonna deal with these ice zombies,") you can bet that his world would not feel the way it does.
Obviously, you can also take this too far the other way by doing things like having a made up term for every other noun even when it would work to just say the normal word, but if your fictional world is loosely inspired by a certain time period, making sure that reflects in your setting's language is good writing, not bad.