In any case, as you say, it is nothing new, and open to everyone with enough money (as Clinton had). If you want to suggest it was unfair play, then maybe you should rethink how the president is elected in general. Should TV advertisements be allowed? They also manipulate people, and favor the candidate with the most money. How could you ensure that people vote without having been manipulated? Maybe nobody should be allowed to consume any media for 2 years prior to the election?
There are also presumably entities with far more data available than Cambridge Analytics, as have been mentioned on HN frequently before. Advertisers have been collecting data on people for a long time.