Why do Atlas Dems keep talking about Kamala Harris as a potential candidate?

[America Needs R'hllor]

She was AG and had a progresssive record, so she should be able to get both wings of the Democratic party aboard if she chooses a VP from the Sanders wing, like Sherrod Brown. Also, she could remind people of Obama.
And regarding what you said of Keith Ellison, personally I don't support him unless he resigns from Congress, but you can't say the hype about him is in any way related to his race or religion. The hype is because he's from the Sanders wing, and many believe that this is the approach the Democratic party should be taking to win in 2018 and 2020.

[America Needs R'hllor]

She was AG and had a progresssive record, so she should be able to get both wings of the Democratic party aboard if she chooses a VP from the Sanders wing, like Sherrod Brown. Also, she could remind people of Obama.

Harris is pretty close to the Sanders wing...

That's true, but I think she's not really percieved as a part of that wing. In any case, an establishment-wing VP would be pretty useless because she would be enough to turn out these voters. A Sanders-wing VP would consolidate his voters and appeal to all working class voters (regardless of ethnicity).