The people designated as “campaign trail press” generally aren’t well-versed on foreign policy; their world is polls, pundits, retweets, and so forth, and as such they don’t spend a heck of a lot of time reading up about Yemen. (Not that it would take a ton of effort to do: the New York Times and other thoroughly mainstream outlets have reported extensively on US culpability for the disaster.) This leads to a situation where we end up spending a full week in October litigating the 1996 Miss …
Yet even then, they are often being fed information. See the Ben Rhodes affair of know nothing journalism.
Otherwise, yes, dirty laundry sells. The sex and sleaze get the ratings and clicks, and therefore, the money. The candidates weren’t all that interested in foreign policy discussion, either. As a presidential candidate Trump claimed to making America great. His foreign policy leans to pulling up the drawbridges and bombarding outsiders as necessary. Candidate Clinton helped design the “send advisors, lose slowly” plan we’ve been running now, although the idea certainly isn’t original to her. (Recall, it was JFK’s dispatch of military advisors to Vietnam that grew into that war after a disastrous meeting with the Soviet leader.) She didn’t want to talk about it, perhaps becuase the follow ups to Yemen would be questions about the other conflicts we are involved in that the public know little about.