Completely agree. I wonder how much this varies across cultures on the country level (like how people say the Dutch are blunt).

I think that indirectness emerges when a critical mass of people decide that they're better off in an indirect culture. i.e., thinking "nobody is straightforward with me, but that's worth it because it means I don't have to be straightforward with anyone else". And of course that's infuriating for anyone who would rather take the opposite deal!