With situations you outlined, there are some bad assumptions you're making. First, in the scenario where A gets 40% of the vote and B and C get 30% of the vote apiece, you assert that 60% of the population does not approve of candidate A, despite his win. You get this number by adding B and C together. However, this does not mean that B and C attract equal opposition to A. Rather, it means that 60% of the electorate opposes A, but 70% opposes B and 70% opposes C. A first past the post system does not mean that the candidate is disliked by the electorate if he doesn't receive a vote, but rather he was not the first pick. C supporters may lean more towards A, but see C as the better candidate. However, if C dropped out, they still like A more than B. These metrics can't be accounted in a first pass the post system, which does not care about the votes not received, so long as the winner receive the most.
This is true with the assertion that Donald Trump would not win. All we know is that the support of the less successful candidates meant that Donald Trump was not their first pick, as opposed to #NeverTrump. You can only assume that Trump will get a portion of the support of people who still liked him over other candidates.
If we look at the original set up of a 40%/30%/30% split, Candidate A is still likely to win in a First Pass the Post because he only needs to secure 36% of C's support (11% of the total available voters) to win. Where as B would need to secure 70% of C's support (21% of the total available voters). Keep in mind that C's support does not mean disapproval of A or B. It could be B < A < C or A< B < C. In our real world model, You assume that Kasich Supporters would support Cruise before Trump, without taking into account that Kasiche supporters might have stronger feelings of opposition to Cruise than Trump.
So that's just with some math of yours not with your system.
With your system, lets add to the mix of canadates A, B, C the new comers D, and E. If I arrange my ballot so that C < B < A and never rate D and E because I cannot stand either of them (effectively never voting for them), what happens to my vote if A, B, and C are eliminated? Here my vote is never given to a any candidate because I did not choose either. To correct would you require to rate D and E? If so, what if I use my freedom of speech to still choose not to rate D and E and my ballot is thrown out because it is not complete? What if I do cast a vote for a winning candidate in my order, and still refuse to vote D or E... does that discount my vote?