Bill Clinton saying "We're all Eisenhower Republicans here"
Obama claiming he would have been a republican before the conservative revolution
Hillary trying out her fucking GOLDWATER credentials to get elected.
And there's Biden talking fondly of Strom Thurmond (Although at least he didn't try to claim his political legacy)
Who are they trying to appeal to? Anyone who likes Goldwater isn't going to vote for a Democrat, ever, and anyone else who knows who he was would hate it.
It's good to consider that, but it's also possible (1) this has no real effect or (2) they'd be more successful without it, but for whatever reason it's become "conventional wisdom."
There are all sorts of things people do that don't actually work for them.
There's no proof that they'd be more successful without it, or at least no highly paid consultants have told them that there's proof!