Mob's strong but it slowly becomes apparent he's not the strongest. And as a side note, it's not exactly Mob that wrecks everything but that "power" within him. The point is that Mob holds back in order not to endanger others.
The show's focus isn't the action (which is very, very good) but the characters. The main cast learns from their mistakes and Mob especially gets plenty of development. You could say that "Not everything is solved with violence." is like the motto of the show. For example, the fight with Hanazawa ended with Mob's victory, but actually both of them lost. Mob subconsciously resorted to violence and broke his vow, while Hanazawa had his entire worldview shattered.
I don't blame you if you still feel that the show is shallow, but I think it's really unfair to sum it up as "Mob wins everything". In any case, I think it's worth it just for its outstanding animation.