Anything that progresses the cause of world peace should be unreservedly celebrated by everyone. Trump's 20 steps into North Korea at the side of Kim Jong Un is one of those acts that we all should be happy about.
Trump wants us to think this was all a spur of the moment event prompted by his realization that he was close enough to the DMZ to just drive over and shake Kim's hand. Maybe that is true, maybe it isn't. The unplanned nature of this turn in world history was seen in the scuffle that broke out between North Korean security personnel and members of the western press corps plus White House staffers accompanying Trump. No-one told them what to do about these people trying to do their jobs so they reverted to standard procedure and forcibly barred them from entry to a room.
Now the press is covering that story with almost the same energy as the one that Trump wants them to cover.
Trump loves to break norms and ignore standard procedures. He thinks that only whatever is in his echo chamber is important. He is wrong and it is costing him the adulation he so desperately craves. The reason there are staff and preparations and protocols for international meetings is for the purpose of both parties clearly conveying the message they want to send to each other and their own people. Trump's moment in the history books will now forever be accompanied by a note about North Korean security roughing up his Press Secretary. Who knows how difficult it is to just get together for a handshake? Given Trump's record with Press Secretaries, maybe that is what he wanted.