ZKKfans are just coping because Teach being FV would mean Shiryu > Mihawk, they will cry about this.
Nika is not the saviour of the world he will never be.
There are no simple answers in OP thats why its better than other series.
Nika or Sun God can't change the nature of humans.
As long as humans exist, there will always some people who will kill other people and enslave other people.
Thats why people like Garp, Sengoku, Koby, Smoker, Fujitora are not evil but they still side with Government. Because OP world isn't as simple as you clowns believe.
Thinking that without Imu, slavery and wars wouldn't exist is extremely naive. Even without Imu the OP world would have still same amount of slavers and warmongers.
You might believe Imu is FV but you seriously believe Luffy will fight for history?
He is a pirate not revolutionary.
Same Luffy didn't give af about his father or grandfather, but will care about some people who lived in 800 years before that he never met.
Luffy almost always care about his friends, when it comes to others he doesn't even care his father or grandfather. He is not a hero, he said this many times.