I really disagree that Western clothing like T-shirts and trousers are the most sensible way to dress. It's true that Western clothes have spread around the world, due to their prestige, but, really, the most sensible way to dress is nudity in many cases.
Swimming trunks are a Western, Victorian creation, for example, and they have replaced swimming naked around the world - very unsensible! The most sensible clothing for a region like California is complete nudity, as exemplified by the dress of the native people. The fact that most people in California where T-shirts and trousers is testament to Western influence. In an Easternized world, rather than a Westernized world, I imagine that even non-Eastern people around the world would be adopting hanfu - which, by the way, is comfortable and pleasant, and about as sensible as any Western clothing.