It was never implied once that GV had anything to do with the Void Century or the lore of the series, yes it’s a big battle but not that different from your modern day Dressrosa, Enies Lobby, Alabasta and so on.
Unlike Luffy, who’s the main character, other pirates don’t constantly get into big fight events on a daily basis, so if Ennies Lobby were to happen in Roger’s era, it would be a big deal too
Thing with God Valley is that, since its first mention, it has consistently lost any interesting portrayal Oda may have given it. First, it turned out that the "God Valley" name meant nothing and, far from having anything to do with the Celestial Dragons, they were just salty some country irrelevantly contained the word "God" and decided to celebrate a hunting competition that in itself wasn't anything special since they'd do it every three years. Then we find out that the terrorist who broke too many world taboos came to this island, which was later erased from history by the World Government, seemingly headed to his death place because of a woman.
It is true that it was never directly implied that God Valley had anything to do with the Void Century and the overall lore, but it's undeniable that pretty much every reader expected something different from an island named after gods where every big player from that era met the day the mighty taboo-breaker terrorist died, and which was later erased from history.
Of course something bigger than Shakky's issue happened during the events of God Valley, likely involving Imu and whatever interested Rocks about the censored history of the world, but I think it's undeniable how underwhelming everything regarding God Valley ended up being until now. I mean, the island even looked like the Emerald City from "Wizard of Oz" that Bellamy referred to back in Jaya; only for it to be pointless too.