Trump can't take responsibility for things he says or does. He never apologizes, he never considers the negative consequences of his actions then he cries foul when he is asked legitimate questions. It's never his fault, he always blames someone else. Being asked to explain one's self is not harsh, it's journalism 101.
Hillary Clinton is playing right into Donald Trump's hands by trying to use insults against him. Trump beat 16 GOP candidates during the primary; many of them resorted to insulting the billionaire businessman. These insults against Trump failed during the primary, and could very well fail for Clinton during the general election campaign.
As soon as both parties come to insults and sandbagging, it has become a schoolyard brawl, and is no longer a respectable race, or debate. For the most part, both parties are disliked by a huge number of people, but when they start going at it with insults and verbal attacks, they are just pushing their dislike and abhorrent nature to a higher level.
Much like schoolchildren, politicians often begin to stoop to the other persons level, particularly at the end of a race by posting negative things and by creating a negative campaign. It is the inevitable result of a long stressful campaign where the opponent does not play fair, but it is not honorable.