Considering super brainz has 2 almost impossible to land a abilities, I think it's fine if he has some splash damage. Honestly if you're getting hit by splash damage as a sniper, you might want to reposition.
Captain has a slow projectile speed at long ranges and he's so slow that if he manages to make his way up to a team to use his shotgun, that speaks more to your teams ability than it does the power level of a character.
I think people underestimate how much strategy this game takes. Due to the theme and art style, people think you can just join a game and do well by being reckless and careless. I wish people would play more tactically, then maybe we wouldn't get people complaining on the forums about nerfing things that are fine just because they got their * handed to them.