Mr

I'll be honest, the FORM itself may feel like lazy writing.. But Gohan has been labeled as the successor to Vegeta and Goku since the Cell games when they directly stated he has HIGHER potential then all of them combined..

Which is why he was the only one who could beat cell, this is also why Goku sacrificed himself considering his BIGGEST and MOST significant transformations were AFTER the loss of people close to him like Krillin on Planet Namek while fighting Frieza.

I'd say it tracks with the ORIGINAL trajectory his character was supposed to take before he became a father and husband to Pan and Videl post-World Martial Arts Tournament/Buu Saga

Maybe they could have written it better, but it's been set in stone that he'd exceed their abilities without question and without a struggle due to his potential already being acknowledged. His ascension should have been anticipated, Goku knows the future is made up of everyone who comes AFTER him so it's definitely a proud moment for a guy like Goku to see Gohan finally take his rightful place at the top of the food chain, as it was originally intended of course.

They probably didn't want to steal Goku's thunder JUST yet after the Cell Games, he had plenty of years being the heavy hitter still left in him. We all love Goku, so it was the right play, and it gave Gohan time to figure out what he wanted in life while starting his own family like Goku did to secure his legacy.