The brokered-convention-as-a-frequent-and-good-thing has nothing to do with Trump’s perceived campaign style. To my knowledge he’ made no such official demand (say, as in a loyalty pledge) to the ‘convention’. Frankly, there’s a lot of bravado, bluster and BS going around from both sides.
If anti-Trump forces want to derail him before getting into a convention, then let them try it. But don’t try to convince us that it is a ‘good’ thing on the basis of old and even older elections.