I don't know how much each facet contributes to the continued coverage, but coverage goes to whatever gets eyes on ads (money shows up twice in this case; once for "if it bleeds, it leads" and once for "this happened to rich people.")
Also, isn't it one of the fundamentals of Greek Tragedy that there has to be a fall from a great height? I agree that it's insane that we seem to regard the suffering or death of someone who was living a life of luxury five minutes ago as worse or at least more noteworthy than the exact same thing happening to someone who was living in squalor or anonymity, but does this tap into something about humans? I do think there's a lot we misjudge because we're funny about "loss" contrasted with "not having in the first place."
Then there's the horrorshow aspect. Getting crushed a great depths of the ocean is gruesome and fascinating. It's something that gives you the heebie-jeebies. More tragic? No. More grotesquely interesting? Yeah. Heck, didn't we have a spate of movies in the '90s where half the peril was "deep underwater and could get crushed at any second?" The Abyss etc? It's a thing, so to speak.
And it's circular. There's, pardon the turn of phrase, enough meat on the bones of this story that the "updates" get views, and until that stops, they'll keep happening. I suspect it'll become a footnote before too long, but it'll only happen when it stops providing a monetary return on little or no investment.
I don't discount much of anything noted above, either. Schadenfreude, minor variation from normal, etc... But I do think that the continued coverage aspect is kind of the "bottom line" of the math for whether the above fragments are piquing people's interest. In summary, some combination of these things is keeping it interesting enough to enough people to keep it profitable to run the stories. When this is no longer the case, it'll fade; the site metrics will show it's a waste of pixels to run the updates and the space will be taken up with a Kardashian or pop music feud or cultural slap-fight.
If that's not enough, I just can't come up with a great hypothesis for who benefits from trying to keep it in the public consciousness, unless someone's bringing out a new submersible thriller (hastily assembled docudrama?) and they want to keep a simmering interest long enough to release it. Come to think of it... I'm rolling with that as a backup answer. I think it's a reach, but it does move the goalpost on the RoI math, and a few small news stories are probably cheaper than a lot of a Hollywood media blitz.
