Nothing has changed except all those hardliners in Iran who were against the treaty? They got proved right. And the moderate faction is now severely jaded with US promises, and that poses a problem for any descalation in the future.
I don't see it as a huge setback. "Hardcore" and "moderates" are relative terms. In the end the leaders (elected and non-elected ones) are steering the country toward expansionism, even the moderate ones.
Until there are moderate voices in Iran that support opening a dialogue with Israel, I will treat the supposed Iranian "moderates" with a huge grain of salt.
Some of Trumps foreign policy measures have had negative results. None of them were as cataclysmically fucked up as this one. He turned an enemy willing to engage into détente into and enemy who knows the US won't play fair and will respond in kind.
But was detente in America's best interests at all? The US is invested in the Middle East, and Iran is basically kind of the fire nation that threatens the Middle East. It's no coincidence that the vast majority of the area hate their guts, and even willing to ally with the evil Zionists against them!
The treaty tied America's hands while allowing the Iranians to do as they wish conventionally, and do as they wish with nukes after a negligible delay. It was untenable.