Three observations about Trump and the presser...
1) He's somewhat of a prize fighter who seeks out the opponent's weakness. Knowing public perception of the media is in the basement, he eggs them on and their reaction only furthers the perception. This falls under "they still don't get it". They still don't realize that berating, laughing, and attacking him for 18 months did not work and only served to propel him forward because of that very public perception of media long before Trump even came on the scene. What's that phrase..."hoisted on their own petard"?
Likewise he knew the public opinion on illegal immigration and the fact that his two most formidable opponents in the primaries were Jeb Bush and Marco Rubio who were leaning toward amnesty. He had found their soft spot and correctly suspected they would react negatively owing to Bush's Mexican wife and Rubio's Cuban ancestry. They did, and it didn't help that in responding they tried to twist his remarks so as to suggest he was 100% anti-Hispanic. Dumb, really dumb on their part and the media who ran with it. Jeb and Marco were toast after the 1st debate.
2) I'll grant he talks too much about a "landslide" victory. There indeed have been wider margins of victory. What he should be talking about is his "upset" victory that probably eclipses Truman's over Dewey nearly 70 years ago.
3) Is he diplomatic....hell no! Was Lyndon Johnson diplomatic? Harry Truman? We don't need no stinkin' diplomat other than the Secretary of State. He or she can play patty cake and schmooze with whoever they want that's their job. The Chief Executive's job is to get things done. Trump is brusque and blunt like your typical New York alpha male who gets thing done, and he is doing it everyday which is exactly what pisses some people off.
That doesn't mean he's incapable of being pleasant and generous to those who deserve it....which excludes the press and dozens of do nothing politicians and bureaucrats in both parties.