Yes, we need to grow more independent of the U.S. (while maintaining good relations with it). Investing in a flourishing European arms industry will not just secure our independence and strengthen our common defense. It will also be an investment that pays off economically via jobs created here, corporate taxes paid here, etc.
I wish we could invest into building a more peaceful and just world instead. But that is not what our current situation calls for. Right now we need to safeguard the peace and justice we have already. We've come a long way and mustn't allow an aggressive and ruthless neighbor to threaten what we've achieved up to this point.
The USA has rules around military spending, namely that as much money as possible needs to be spent within the country, they'd expect the same from their allies.