Trump's now trapped in his own two-part tactic of shoot from the lip (no scripting) and say outlandish things in order to capture the news cycle.
He knows he dare not pivot and be too presidential because then this happens: things like this Washington Post article in which policy comparisons with Hillary and his use of a script become the news stories, and neither of those topics help him...or, for that matter, sustain media ad revenue or media "consumers'" interest in him at current levels.
This says more about We The People and the media than it says about Trump.
Most voters don't care about policy or policy comparisons. The majority of US voters reject policy-related news as boring. Instead, long ago (by media standards), they rated more highly content evoking reality TV, specifically individuals having an attitude, being outlandish, or having a strong "personal brand."
I reject the notion that the GOP alone created Trump. The USA created Trump. The majority did it by voting with their traceable, measurable media consumption of dreck tailored to short attention spans, and the media—which is a for-profit enterprise, remember—would be foolish to not curate at least some content in that direction.
Trump facilitates that incredibly well and has done so throughout this presidential campaign cycle.
The media in turn have given him $3 billion in free coverage.
It may not be as literal of a quid pro quo as that, of course. Trump was outlandish in previous presidential campaigns, too, but got little press coverage. However, the electorate has changed, Trump's refined his tactic, and, most importantly I think, Barack Obama isn't the other candidate this time around.
That's why the consensus that Hillary is a boring candidate is a great asset to her now in a way it wasn't when she ran against Obama. Obama wasn't throwing rhetorical bombs. He was often inspirational. In fact, Hillary tended to get notable coverage especially in those rare moments when she was provocative, deliberately or otherwise, like her May 2008 gaffe, “We all remember Bobby Kennedy was assassinated in June in California.”
Hillary will get less coverage than Trump. But the coverage isn't going to offend nearly as many people nearly as much as Trump's coverage will.
But, if Trump turns away from such a style, the race becomes for most Americans one of Boring Candidate vs. Boring Candidate, and in that climate, Hillary will definitely win the news cycles because then her presidential demeanor, gender, more in-depth policy proposals, and qualifications stand out more.
Trump knows he can't afford to be boring, so he figures he might as well at least pander to his base, and pray to the ghost of William Randolph Hearst for some sort of September or October surprise that will help him, hurt Hillary, or both.