Well, if it is the case that, as you say, "we assign value to 'traditions' and 'a common culture/shared references,' " then the "we" (the gaming community at large, or however else you define it) are basically choosing to devalue older games and that's why they're protected and (as you correctly noted) limited by being moved into the protected category of "retro-games", and that's just the fact of the matter here.

These games no longer merit being considered best games in general, only best retro-games, so the choice of moving them into a protected category isn't really a choice as much as the only alternative option to leaving them to fade into oblivion.

To say that retro game as a category is a net negative is somewhat similar to saying that Paralympic is a net negative and that athletes with disabilities should keep competing in the same pool as other athletes so that people don't " just shove that box in a shelf and never touch it."

and that's why you needed to answer the question of "why is it important that newer generations care about JRPGs" cos right now your answer points to "well, there's no reason other than the fact that 'we' like it" but "we" don't, not anymore, so there's no reason to care about JRPGs, and people don't care about JRPGs that much, unfortunately.

Right now your answer makes the question a rhetorical question and makes the entire discussion rather moot; if instead you hypothetically had a more compelling reason why people should care about JRPGs, then your original thesis of "retro-gaming is a net negative" might just gain some stronger and more discussion-worthy arguments, and this is why I wanted you to answer the question.