While I do think the EU is lacking the balls to do this, there's also some strategy to consider here. It certainly would be lovely if the EU would be more defensive, but also more damaging to the EU economy (at least in the short run, probably for a long time).
China is being painted as enemy number one, and there's long-standing beef between the countries. Trump lost or is losing the trade war, and needs to make himself not look weak. Meanwhile China wants to project strength internally. Whatever is happening between closed doors, China has everything to gain from humiliating the US at this point. Trumps incompetence is already evident, they just need to fuel the flames.
With the EU, the situation is wildly different. EU doesn't really want to project power, they want to project exactly as much power as is necessary not to seem weak but no more. It wants to show that it's a level-headed free trade partner ready to take the lead in the free world, the fairest and most stable market in the world.
...that's my take on it anyway. USE! USE! USE! USE! 🇪🇺
I'm not 100% sure about the economics of tariffs, but my interpretation is that the US are shooting themselves in the foot more than us. And if we can project an image of a stable level-headed trading partner and create good trade relations with India, China and countries in Africa and South America that might be more valuable in the long run than our US trade relations.
Basically, if US wants to hamper their own economy, let them. Meanwhile we'll be Open For Business™ and picking up all the good stuff they left behind.