I usually find companies' doll blurbs to be pleasant enough. I think Volks' blurbs strike a good balance considering how bare-bones they are. Danny Choo's are a great example of what not to do.
As for my own dolls, I do assign them personalities and character. It's not a conscious thing on my part, I just kind of let the doll manifest as I look at her, dress her, and pose her. One of my girls turned out to be kind with a quietly lewd streak (she always seems to have her hands on the others), another is a grumpy door kicker, a third is mischievous, a fourth is a simmering little sexpot who has no actual experience and has her bluff shattered easily, and the other two are character dolls who haven't yet gained enough of a signature for me to tell them apart from the characters they were made for. I also have one Mini Sweets doll whose only personality in my mind is "smol".
I've seen other people go to great lengths in their doll profiles, some scarily so. If that's their thing then more power to them, I says.