The problem is that Tomura is one of the hardest types of villains to write or characterize well. Specifically, a true Nihilist. The problem is writing such a character tends to leave readers/viewers with the impression of immaturity or just being whiny. I'd have no trouble thinking of plenty of examples of such "boring" or "weak" villains, but as for a strong example....I can only think of one off the top of my head. That would be DC comics Owlman, in his most recent Earth 3 incarnation, primarily the Crisis on Two Earths animated film but to a reasonable extent in the comics as well.