People fell in love with Obama way back in 2004 because he had an otherworldly charisma, undeniable intelligence, compelling seriousness combined with a much-needed relation/commitment to real people/struggling communities that Bernard can't come close to touching. And of course she's running on a continuance of Obama's administration. She's a life-long Dem, was part of Obama's cabinet and they have always had very similar believes! Even back in 2008. Hell, she was more liberal than he was, arguing for things like the public option lol.
But what's also true, is that she's very much like Obama in terms of how they think and would proceed as operators in the White House. He's a lot more charismatic, obviously, but they're both not too fond of the silliness of campaigning and what goes with that on a day-to-day basis. They want to actually do the job! They're both incredibly wonkish, prepared and liable to get really deep into the meat and potatoes of things. Ask them a question and they'll talk your hear off explaining the nuance and reality of the issue, which, as seen in this interview/his meeting with the NYDN board, is a real contrast to what you see from Sanders.
Most importantly, Hillary, much like Barack, knows what's really required to get real progress through the meat grinder of the current political climate of the House/Senate. And actually has the ability to get that agenda done.