Bolton was scary enough that I was always worried that he'd go behind the president's back to start a war, like with all of that shaky Iran intel. I guess at the end of the day he didn't have the juice to actually kill US troops to start a war, but God damn am I glad that threat's not hovering anymore.Bolton was/is a hammer. A hammer that will not be needed until after the 2020 election.
We will not be leaning on the DPRK for a while (going into the final round of meeting/talks relatively soon I assume.), and we sure as hell aren't getting involved militarily with Venezuela or Iran.
Bolton is the Warhawk Supreme. He knows it, DC knows it, and the World knows it. Functionally speaking, Bolton is/was the "bad/evil cop" to Trumps "reasonable cop".
Many non-interventionists will celebrate Trump "resisting NeoCon policies", while functionally there will be no real difference in policy compared to the pre-Bolton era. It will please a fair chunk of the electorate however.
Bolton also make a bunch of reforms to the National Security Council while he was there, and did not make many friends. Trump can go through and say that "oh my, these are not reforms that I wanted to make." And he "fires" Bolton, but then leave those reforms in place.
It is as simple as that.