The two parties provide the opposing agendas which dominate, and the particular characteristics of each candidate are secondary.
Especially when neither party has much to offer the average citizen any more, they have built their strength traditionally on low voter turnout where extreme factions loudly broadcasting gradually become over-represented in the most polarizing way.
As cycles continue only the most polarizing issues drive the turnout, and for turnout to grow beyond a certain point the majority of the potential voters must perceive the other party as a more serious threat, when compared to any security offered by their own party which they (might) have chosen because they found it less offensive (maybe only in past cycles too).
The parties no longer need to have as much to offer the average citizen as cycles go on, when they can get contending turnout from their own extremists combined with orders of magnitude more sympathizers who can be convinced to strongly fear what the _other side_ could take away.
Seems like after a party has been around for longer than any living person, they will not get support by having more to offer average citizens than in previous cycles, only by taking less away from them.
So the average citizen hasn't had a positive outcome within reach for a while.
Now it's too late, these top candidates are realistically as youthful as you can get compared to the grand old parties themselves, and regardless of personal integrity or leadership style can not offer anything above that from the parties alone.
Even in the case of Trump's extreme personality, which the Democrats did not even try to nominate a candidate having that feature, so this element was as one-sided as you can get.
I saw agreement from both sides that a wet dishrag could defeat Trump if only 270 electors represent voters who just plain dislike or hate him. Conversely it was recognized Trump would win if he had merely 270 electors of voters who dislike or hate one or more of the current items on the Democratic party platform.
Neither strategy can offer anything to the majority of the citizens in the political middle, the true average citizen, since turnout has been driven by fear not opportunity.
Building a coalition from a carefully-crafted extreme attention-getting position, and pushing hard from there so the other side ends up below the 50 percent needed to be in power, has turned out to prevail over representing even the middle 50 percent of voters which is how it was supposed to be at a minimum.
So once the issues and/or personalities representing them have reached full polarity, 50 becomes more of a constant to be converged upon from afar rather than a starting point to build a majority from in both directions.
Resulting in half the voters who turn out, and half the politically centrist citizens (which is a much larger group by a variable multiple of active voters) who will always be dissatisfied and these are two different groups (but having significant overlap), the latter of which is the core of the majority that all parties are supposed to be treating as constituents.
But the core of the majority in the middle doesn't have a voice because they don't have any party which represents them any more, the parties are doing other things with the money and the concerns of centrist citizens are given lowest priority.
The party gets more votes over the long run by fear-mongering against the other side regardless of who the candidates are at the time, and only declining resources can be justified which might actually benefit the majority of citizens.
Problem is, the majority are voting against their own best interest because their own best interest has not been available for a number of cycles. Rather each side votes against what's perveived as the other's best interest instead, since that's the only thing at stake anyway.
So the majority of voters end up speaking for the entire population as designed, but all votes are cast against someone's best interest because the minority party is voting exactly the same as the majority in this regard.
So it's unanimous by both parties that as few of the average citizens as possible should have their best interest be served, and to redefine democracy in that direction can not be accomplished during a single cycle or maybe not even a single generation.
Ending up with the choice between a trustworthy Joe and a dishonest Don the thing that doesn't really matter to half the voters as much as it should.
It would probably help if there were parties which were younger than the candidates.