Touhou characters have plenty of defining traits. Marisa is sociable and charming, yet studious, honest and hard working. Reimu is transient and a bit blunt, and treats everyone in the same disinterested manner (except Kosuzu because shit writing I guess?). Sakuya is dedicated, haughty, and aloof, and Youmu is immature, loyal and a bit dim. They all have these nuances that, while not directly spelled out, paint a portrait of a colorful and intricate cast of characters. I believe this is why many animefags have such a difficult time grasping the canon 2hus, and why fanon personalities are so common. It's because they're just so used to these copy pasted archetypes, where a character is defined by a few very explicit traits, and often struggles to venture much farther beyond their cliches. It's far easier to digest, but nowhere near as substantial as the well written 2hus.
But that's just my opinion on the matter.