question of the century.
Gorosei, like a lot of characters/Events in OP are just there to eventually serve the plot when needed. Oda has introduced most characters with the intent of probably using them "soon". The problem is One Piece is so long that some of these things got pushed WAY back. Like they were introduced when Skypiea at one point was considered "50%" Of Luffys journey lol. When you think about some other examples, this starts to make sense....
- Elbaf has been teased for 20 years
- Vegapunk has been teased for 15 years lol
- Kuma as a character was featured heavily post TB to Marinford, but then was put on the backburner for some major plot with Bonney/Sabo
- Kong's only been seen once halfway through the story lol
- Shanks and Blackbeard have had very markedly 'low' roles in the story thus far (just big influence and hype moments for sure)
- Mihawk is just like the 2 above, just less so
- Dragon's almost just like the Gorosei, but seen even less and has been around even longer
- Major characters like Garp, Sengoku, Akainu, etc wouldn't have gotten the roles they had if it weren't for Marineford. Without that arc, we'd still just get occasional teases of who they are.
And there's definitely more I'm forgetting. I'm sure all will have great payoff for sure, it just this manga has pent up many of them before 2 of the 4 Yonko, but even some Shichibukai.
Luckily for years we've been on an uptrend of resolving major plot points. Finishing Dressrosa/WCI/Wano is a big deal because of the 3 Major villains it ties up. But now somehow Oda has to do everything I just mentioned above and so much more lol