The first election I paid attention to was the 1972 Nixon-McGovern debacle. I don't think Sen. McGovern could have beaten Pres. Nixon even if he had run an excellent campaign. Turns out, though, that Nixon would eventually do it for him.
I give Sen. McGovern full credit, though, for opposing the Vietnam War. That war was wrong in so many ways, and as it headed toward its third decade, it needed killing. Having the standard bearer a major party - the historic war party - oppose that war help speed its end.
McGovern stood for good causes all of his public life, in office and out. He did not cash in in retirement; in fact, he didn't really even retire.
By opposing the Vietnam War, though, the Democratic Party did acquire a reputation for softness. This was mostly undeserved, but not wholly.
It is fitting, therefore, that the end of George McGovern's honorable life should come during the term of a Democratic president who is clearly not soft. An era has ended; another has begun.