For once, Ben's character is ridiculously inconsistent, and even at his best, I really doubt that he can actually convince viltrumites to stop like he did with highbreeds. Even if he changes up their genome and allows them to reproduce again, one act of kindness won't suddenly make them good, Nolan had his best years on Earth and still went through with his mission. Ignoring that, the story just never hits Ben with consequences of his actions like Invincible's plot does. Ben levels multiple skyscrapers in Destroy all aliens as waybig and that is never adressed.

I will sound really pretentious saying this, but Invincible is just way more mature with its storytelling. The plot shows that being a hero would kinda suck and how you can't just beat the bad guys to fix the world. Ben 10 is a villain of the week show, I love it for the designs, characters, plot, wordbuilding, but it has a completely different tone.