And yes, she ignored Bill's advice totally. Top that with being lazy and ceding the campaign trail to Trump, she lost. Hillary made 71 campaign appearances, visits, rallies to Trump's 116 from 1 Sep through 8 Nov 2016. In Wisconsin, it was Trump 5 visits, stops to Hillary's none. Michigan, Trump six, Hillary one. Pennsylvania was closer, 8 for Trump, 5 for Hillary. She even ceded electoral vote rich Florida to Trump, 13 visits, stops, rallies for Trump, 8 for Hillary.
I'm sure Biden won't make those same mistakes. Especially ceding the campaign trail. If he does, then like Hillary, he deserves to lose.
I think you are correct that Biden is a more natural fit for many of the swing-Trump voters (though I wonder the extent to which they will be naturally motivated to confirm their 2016 choice), and is a greater danger to those 78,000 votes that flipped three states...
...but I'm not sure how much Biden's advisors are going to want him on the campaign trail. Just as he won the primary by being the only plausible Consensus Not-Bernie, I would suggest his strongest position in the General is being the Consensus-Not-Trump. He's best running as Generic Democrat on the ballot, not a flesh-and-blood grandpa that people can see calling them a lying dog faced pony soldier on a daily or weekly basis.