This wasn't anything new for most people who knew just a little bit about how FB worked for 3rd parties.
What changed was Trump. Had this been Hillary we wouldn't been talking about it at all and I am pretty sure FB wouldn't have been called to the hearing.
So I would say it's mostly a media driven thing but of course don't have any final proof. Just pretty sure it wasn't the privacy part that was the problem but rather Trump.
I responded to someone drawing similarities between Cambridge Analytica and Elon Musk's joint toke, claiming both were examples of "stupid media freakouts" which caused a drop in the stock price of their respective companies.
I think those 2 media events are very different from each other and have very different consequences for their respective companies. I might be proven wrong though if Musk is brought to task in front of a senate committee for his pot-smoking ways.
I agree with you that Trump's election may have made it more likely that Cambridge Analytica became a big deal in the public eye. There's more controversy to fuel media frenzy if the person who got elected is seen to have unjustly ascended the throne.