She's a newer face, so she can run more effectively as a change candidate.
There isn't a perception that she succeeded due to a husband or powerful relatives.
She's a minority, so she doesn't have to try as hard to win those votes.
She's a younger progressive, so she'll have an "in" with the activists. But 13 years as a prosecutor, and 4 years as a Senator in the minority party will limit the amount of controversial votes that can scare centrists.
She has some disadvantages as well (no kids, a Californian might not appeal to voters in key rust belt/ southeastern swing states.)
I agree with pretty much all of this, but I feel a liberal San Franciscan would be just as successful in the Midwest as a born-to-wealth New York billionaire. It's mostly about the issues
Remember that you have to
get people to vote for you, and a Midwestern progressive would do this more naturally in the Rust Belt than a Californian or New Yorker.