We have laws explicitly for imposing tariffs for these reasons (like Trade Expansion Act of 1962, Trade Act of 1974)

The difference is they have to go through administrative procedure, and are subject to more judicial review to ensure administrative process was followed. Even if its a fig leaf in this administrative, its a tad slower with higher judicial oversight.

What Trump wants to do is impose tariffs on a whim using emergency powers where administrative procedure laws don't apply.

So the hope here: we have at least more predictability / stability in the tariff regime. But tariffs aren't going away