We are not talking youth really, we are talking middle age. While constitution says you have to be at least 35 to run, serious candidates have always been at least in their 40s. Unlike
some, I do not advocate 20-somethings should be president. But at the same time, it is hardly controversial that at an advanced age both physical and mental faculties start to decline.
If you have an older candidate, you might want a younger running mate, if for no other reason than to hedge against the risk of both of them becoming incapacitated due to age-related risks.
Nothing really. But presidential candidates will usually seek to balance their ticket geographically. New Yorker Trump picked a mid-westerner Pence. Obama, from Hawaii but living in Chicago picked Biden from Delaware.
I can't see the any great benefit to youth when the time these people have to influence the country is so short. We are looking at maybe 16 years in the Presidency to effect change if both of them win two terms in office and that will most likely the time it will take to turn this country around, given the damage that President Trump will do by the time he leaves.
8 years is two terms. Biden will be 78 at inauguration time, meaning he will be 86 after two terms. At that time Warren would be 79 herself. People in their 80s definitely slow down both physically and cognitively, and are at an increased risk from all sorts of illnesses.