A reasonable test of motives is whether the people who are advocating that we bomb the shit out of people for humanitarian reasons ever advocate that we do anything else whatsoever for humanitarian reasons. In our elite discourse, the answer is usually no.
Our country increasingly refuses to take in refugees and we can't even mount a humanitarian relief mission to Puerto Rico (Nobody knows in America...). Obviously Trump is more callous about such matters (as Trump is more callous about all matters), but we weren't exactly bombing the world with food and hospitals before Trump.
tl;dr: Most of our elites love war. I am not sure why. But any excuse will do.