NiKo has had amazing character development since he joined G2. It's true. He seems to really get along with his teammates and be a positive influence on them. But he does really have some problem with mentality, I refuse to believe it's a coincidence that the best rifler of the past decade has neither Katowice, nor Cologne, nor a Major victory. He has never won a single one of the most important events despite how long his career at the top has been.
The trade wouldn't make sense anyway, because Rain and Karrigan wouldn't want to play with NiKo again, Broky probably neither, and G2 would have to make M0nesy into their star, and the whole thing about the Kovacs playing together would just be gone. But the consistency missing on G2 is on NiKo, not HuNter. NiKo is the one who disappears in important matches, so looking past the thing of the players themselves, Ropz stability and team-spirit, while being slightly less good than NiKo, and less impactful maybe too, could make G2 as a whole more stable, which means they would be able to win tournaments, since their ceiling is high enough anyway, and they have a star-worthy player in M0nesy. FaZe right now has no star, so putting NiKo there would catapult the total ceiling to insanity. FaZe could pop off far more than they can now and G2 could be consistent.
Basically your argument for HuNter, I would use for NiKo. But either way, it would never actually work.