So I should be writing a serious analysis - particularly since we now have vice presidential candidates.
Putting aside my feelings about the candidates themselves, let me be completely and utterly bi-partisan here. I have no interest in what their children say. Unless the children have some significant achievement in their own right, there is little reason for them to be addressing the convention or the nation. It is however an interesting illustration of the concept of semi-institutionalization.
First - I do not mean to criticize Chelsea Clinton, Ivanka Trump, Donald Trump Jr. etc. I am sure they are all perfectly nice, charming people. But their primary qualification is their parentage. Most of their professional achievements involve having gone into their parents' business. Good work if you can get it. They are all young and may have substantial achievements ahead of them. Consider George W. and Jeb Bush - there is little doubt that they were helped immensely by have a president for a father (and a Senator for a grandfather by the way.) Nonetheless, THEY won big elections. That is an accomplishment of some note - no matter what kind of help you get.
Nonetheless, nominees keep trotting out their children to give humanizing testimonials. Pundits and partisans cite these articulate children as evidence that the candidate is a good parent and thus a good person and fit to be president.
I am deeply suspicious as to whether any of that is true. Giving a good speech is not magic, it is a skill that can be learned. That the children speak well of their parents is hardly remarkable. Would they really stand up before the world and say, "My father/mother is a crappy human being who never paid any attention to me! Do not vote for them!"
A Long Job Interview
The Presidential campaign is basically a very (very, very) long job interview. Most jobs are a combination of explicit and tacit skills (hard and soft skills if you prefer.) Explicit skills usually have credentials. A dentist for example has a degree and passes exams. In the case of tacit skills you hope that they are either intuitive (like getting along with people) or will be learned on-the-job.
When you are hiring someone you are naturally evaluating their skills, but you are also making sure they aren't crazy. I don't mean to mock mental illness here - that is a serious issue. But we all know people who just kind of radiate negative energy. If you bring such a person into your workplace you open the door to expanded gossip, backbiting and distraction.
That is why the last question of a job interview is always, "Is there anything you would like to tell us about yourself?"
It is one last check to see if there is anything fundamentally off about the person.
That is what the campaign trail is about - we are trying to figure out if there is something off about the person. That determination can be based on very superficial and subjective criteria. But we have to consider them. (Because sometimes a superficial oddity does indicate something deeper.)
So the candidates trot out their children, who dutifully tell cute stories indicating that the candidate is a regular person who does normal and very nice things - all in an effort to show us that they are ok and we won't regret seeing them on TV for the next four to eight years.
A semi-institution is something that is not required but has become expected. The president does not have to meet the VP every week or give them an office in the West Wing. But it would look pretty bad if they did not provide these perqs.
Same now with speeches by the candidate's children. It is expected. It seems unlikely that people will vote for a president because their child gave a good speech. But, if a nominee's offspring did not give at least a competent speech - or gave no speech at all - we would wonder what was wrong. Were they a bad parent, had they messed up their child somehow? Maybe they shouldn't be president after all.
Nixon once said, "Your vice presidential pick can only hurt you." When you are president, that goes for a lot of things.