Best for the country? No. Best for Hillary? Yes. Why do you think the DNC helpfully scheduled as few debates as possible and put them on at the worst times when Hillary was clearly leading? And when Sanders became a threat, suddenly more debates were necessary? It’s all about doing what’s necessary for Hillary to win.
Clinton’s best scenario was a series of largely unopposed primaries that made her look inevitable and a coronation at the convention with the entire party rallying around her as the obvious best choice for president. She could have skated through that with bland speeches guaranteed to keep as much ammunition out of the hands of Republicans as possible.
Her nightmare scenario is a long campaign against a left-wing populist who would force her to tack left to win the nomination, leaving her vulnerable in a general election. I’m familiar with this process - it’s what has been destroying Republican candidates for a long time. The ones who refuse to tack hard right vanish, and the ones that play the game win, and then get hammered for the right-wing positions they were forced to take to win the nomination. Their ‘no tax hikes under any circumstances at all’ campaign pledge comes to mind. That was forced on them by Grover Norquist and the power he had over the ‘base’.
Also, a narrow win against Sanders could result in a convention that’s not so much a coronation as a conflagration like 1968, with hordes of protestors outside the convention halls screaming about social justice and a rigged system. And the absolute worst case: Bernie spinning off a third party run that saps the base and leaves Clinton with moderate Democrats and little else.