Some details here.  This isn't as odd as it seems once one recalls that what attracted Trump to Mitt Romney as Secretary of State was that he "looked the part" (remember, this is an ignorant man, whose view of everything is through television).  Tillerson looks the part, and he has two other virtues from Trump's point of view:  a businessman and someone who is on friendly terms with Vladimir Putin growing out of past business dealings.  I view the latter as a positive, since I still think reducing the risk of nuclear war with an unstable ignoramus in the White House is paramount.  I also note that when Tillerson was head of the Boy Scouts of America, he was instrumental in lifting the ban on openly gay Scouts participating.   Again, against my very low bar of expectations, this would probably be a salutary outcome.  Hopefully he and Secretary of Defense Mattis will prevent Dopey Donald Chump from annihilating civilization.