I know I wish that there were more policy issues on either side. I know that I think there is too much focus on lurid tales of aggressive sexual advances.
However, I think there's a reason for that. For Donald Trump, Trump himself is policy. His admirers don't admire him because they have listened to what he would do as President, and agree that that's the right way to go. His core supporters admire him because he is Donald Trump. He's a billionaire businessman, and they think a smart, successful, guy is what this country needs.
Among Republicans for whom Donald Trump was not their first choice, or who may have been far down the list of choices, they will vote for him because, whatever else might be true, he is still more likely to pass a tax cut than Hillary Clinton would be, or more likely to appoint a conservative Supreme Court justice than Hillary Clinton would be. However, those people opposed his nomination. For his core supporters, the issue is Trump. He was supposed to be the great leader that would make America great again, through some combination of intelligence or business savvy or just plain fighting spirit that would tolerate no opposition. This guy was going to get things done!
So, Donald Trump himself really is the issue. Much more so than for most candidates, personal attacks make more sense. He has sold himself, not his policies, as the leader that can make America great. To refute that, it is necessary to expose his character flaws.
