Trump's (presumptive) nomination was a big surprise to me. However, in retrospect, it looks less surprising. Trump was always going to attract a sizable minority, and there were really no other compelling candidates in the race. While I'm sure that the majority of Republican voters would prefer "not Trump," who that "not Trump" candidate could be was never clear. At the end, well, I am not certain that I wouldn't pic…
Last year, the 2016 GOP presidential candidates were referred to as a "Republican dream team" by Karl Rove. That was true only by comparison with the 2012 field, which was more like the Republican clown car.
Really, the disappointment here is that the candidates just weren't very good. The choices were a few second-rate governors (Bush, Kasich) and a bunch of far-right nuts. None of them would measure up to Eisenhower, or Reagan, or Bush I, or even Nixon.
This setup where you become President by raising your own money and running your own campaign isn't working.