Complaining about mean tweets or other negatives is pointless.
Maybe, but my complaint is that this is an incredibly easy fix for anyone with even a little self-discipline. By showing some, he would gain way more "fencesitting" supporters that otherwise agree with many of his policies than lose the small percentage of "we love Trump being mean" supporters. That he can't do so is a weakness, IMO.
On the campaign, I heard an interesting hypothesis this morning: Haley is staying in till the bitter end with part of the strategy being that there could be a "black swan" event for Trump that will take him out. This is not necessarily a bad strategy if you remove the bias of who you like or don't like. Trump has so far come out strong after each attack, but there is a not low possibility that the establishment will find a way to destroy him. Haley figures if she sticks it out and is "already there" that she will be the obvious nominee.
As of now it's 107 Trump to 17 Haley, with 1215 needed to win. So while Trump is killing it now, you just never know.