It is useful for the president to have emergency powers. However he should have been impeached for abusing emergency powers in a non-emergency. Same for his invasion of Iran - Iran has been building long enough that he had plenty of time to go to Congress for permission if he thought attacks were needed.

Emergency powers should only exist for things that need a very quick response. There's no reason for tariffs to be an emergency power. There's no emergency so urgent that it can't wait for Congress to convene and pass a law enacting the appropriate tariffs. The only reason that power exists at all is some mixture of Congress being too trusting of the President, and Congress not wanting to actually pull its weight in the government.