I used to main Mundo.
I enjoyed trolling people with his unlimited Q and tanking 20 tower shots during teamfights.
Then I started playing other champs. Honestly his kit is pretty garbage compared to most champions.
His Q is fun. His W is trash unless the enemy is just piled up. His E is fine I guess. His ult is stupid.
He's uninteractive and boring to play. He's not good at ganking. He's not great for peel if the enemy knows how to sidestep at all. He's basically just a big ball of health that you can easily maneuver around and can largely ignore in team fights. The only place I feel he really shines is in 1v1 and you'd have to be insane to take duels with him, or one of those people that runs in a straight line and refuses to stand behind minions. Or if the team just focuses him all game which if they know him at all they won't.
Can we just rework his kit? He feels like garbage to play and honestly the only thing that makes me come back to him at all is the Q trolling when I'm bored and don't feel like playing a champ that can actually carry out a game.
I love Mundo. His stupid lines, his character premise, his goofy look. But it doesn't even make sense to play him when there are multiple champs that do what he does better.
He didn't need a damage buff. He needs a full kit rework.