One MAJOR reason is that voters love personalities. And look what that "liking' has got us recently. George W. Bush, Bill Clinton and Barack Hussein Obama. Possibly the best person to run this country would have been Fiorina but she has little personality and she is a REPUBLICAN woman. Kasich has a better personality than THE Donald so maybe the Republicans will ignore Kasich's poor vote support and nominate him.
I have no idea what the Republicans will do if they do or don't have a convention. But you can bet it will be wrong if they don't select the [person to run against Hillary that has the most supporters and delegates.