I've been following politics with a passion for a lot of decades now, and I do not recall EVER that the issue of whether a Vice President pick was qualified to be President ever came up until McCain/Palin. Maybe a little bit when Perot picked Colonel Stockdale, but even that was very low key and nobody suggested that it in any way affected Perot's electability.
And I don't recall a Vice President pick that the opponents of the GOP nominee liked. Especially in modern times. Who had ever heard of Spiro Agnew? When he resigned in disgrace, Gerald Ford was a good pick but had the sad distinction of being both Veep and President without ever being elected to either office. The media was furious with George H.W. Bush when he named Dan Quayle his veep. The Media never saw that coming and made him an object of ridicule from day one. They also hated Dick Cheney from day one, but couldn't make him an object of ridicule so turned that honor onto the President.
So why was Palin such a big deal? Because she was charismatic, funny, beautiful, and therefore a huge threat? So she had to be humilated, marginalized, trashed, demeaned, and disqualified?
Don't give me her not knowing her geography, history, world politics crap unless you acknowledge that the current occupant of the White House was equally ignorant, made just as many gaffes, and was pretty clueless about how it all worked. He was the one who so arrogantly criticized the Bush administration for not pulling Arabic translators out of Iraq, remember? He said they should be taken out of Iraq and sent to Afghanistan. (Where no Arabic is spoken.) More than once he made major mistakes in demanding that the U.N., most especially the U.N. Security Council, do something when that something was not within its prerogative.
And Joe Biden? The lovable clown? Have you seen anywhere near the ridicule, scorn, and demeaning characterizations heaped on him?
Sarah Palin may or may not have accomplished herself in high office. But she sure as hell wouldn't have done any worse than what we've had. And most likely would have done a far sight less damage. But every stumble would have been blasted for days on end and she would have gotten no credit for anything done right.