Do declaratory positions matter?

I cannot come up with a scenario in which the US' declaratory position on use of nuclear weapons impacts the behavior of any international actor. A declaratory position that the US will not use nuclear weapons on non weapons NPT states does firm the international moral consensus against use of nuclear weapons, but do not do it as much as a stronger position that the US will not use nuclear weapons first would.

Iranian strategists are aware that the US could use nuclear weapons on Iran. Even given that, though, Saddam Hussein in 2002 and 2003 would not have allowed an invasion force to position itself on Iraq's border if he had nuclear weapons or a reasonably rapid capability to build nuclear weapons. Iran starting today would not allow an invading force to build up on its borders. The US declaratory position does not impact Iranian considerations at all. I can't see how they impact North Korean considerations, Chinese, Russian, Brazilian, Israeli or anyone's strategic considerations in the world.

If the only impact of a declaratory posture is to impact a general sense of moral distaste for nuclear weapons, it may be best for the United States to adopt a position like that of Iran, that it is immoral to use nuclear weapons and the US does not intend to use those it has.

There are headlines that the US carves out exemptions for Iran and North Korea to its stance that it will not use nuclear weapons. From what I've read, exempted are countries that have not signed the NPT, countries that release themselves from the NPT and countries in violation of the terms of the NPT. The US stretches to say Iran is in violation of the NPT, but I really cannot figure out why I should care. It does not impact the situation on the ground in any way. But either way, Israel is also exempted from this new declaratory posture, as are India and Pakistan.

The new posture is a mild provocation, not nearly as important as the support the US gives to Iranian separatists or US efforts to sabotage Iran's nuclear program on the ground in Iran. Unlike the other provocations I've listed, I don't think changing the posture would be a necessary trust building step of the US was to want to improve its relations with Iran.