The "tragic flaw" is a more useful frame for analysis of subsequent Western tragedy, which was obviously heavily influenced by Aristotle's Poetics. However, Aristotle's analysis of tragedy in Poetics is almost solely an analysis of Oedipus: if he was wrong about Oedipus, then his argument for the "tragic flaw" doesn't have much else support. Indeed, it's not a very useful analytical tool when applied to ancient Greek literature, as opposed to subsequent Western literature. What is Achilles' tragic flaw? That he was jealous of his honor, a completely admirable and noble thing for a bronze age warrior?

In contrast, Walter White does indeed have a tragic flaw: he is prideful. His ordinary, stable life as a high school chemistry teacher was less than he felt he deserved, and when his cancer diagnosis disrupts that status quo, he is set on a path that ultimately destroys him and everything he cared about. But here we have an instance of tragedy written after literally millenia of Aristotle's mistaken analysis of Oedipus defining expectations for tragedy.

There's plenty else in Poetics that is very useful, and obviously its influence on literary criticism and analysis is profound. But one of its most famous findings is, well, tragically flawed.