Does having the knowledge make the game more fun and interesting? Does it offer the players a chance to learn more of the lore of the setting and become immersed with it?
I remember a published adventure once that asked the players to make a difficult roll, and it was attached to a lengthy bit of exposition about the origin of strange ruins, speaking of an ancient, but now lost civilization of magically advanced people who traveled between the planes of existence, spreading their culture, before mysteriously disappearing. It was only tangentially connected to the adventure, but quite fascinating. And it was entirely possible for this knowledge to never have been learned by the PC's at all!
I didn't even have them roll, why would I? When I play, stuff like this is what I live for.
Last night (Sunday), in a Tales of the Valiant game, we were searching for a rare herb to cure lycanthropy (our Barbarian had gotten bit by a werewolf). While there, we encountered an ancient construct trapped beneath rock, and a strange orb wrapped in some kind of living cable that attacked us while the orb attempted to control our minds. We couldn't destroy it, so we eventually figured out how to bury it and cause it to go dormant.
We were very confused by what it was, and why it was there. The GM told us to make a check, we all failed. "It's very interesting", he said, "I wish you would have made the check." Internally I was screaming at him. WHY DID YOU MAKE US ROLL, THEN?!
You could argue that lore is a reward that has to be earned, but so many moments like this being gated by random chance feels wrong to me. What if it could have led to more interesting further adventures?
Sure, the old school approach is to seek out sages and ask questions, but I've seen this play out many times- the party will get distracted by other things and likely forget about it, unless it somehow becomes relevant again.
Also, not to disrupt the conversation, but what does this have to do with the Fighter, specifically?