Because many US companies have been at the receiving end of unfair trade practices, copyright theft and blatant IP violations from the mainland. It's good that we are finally doing something about that.
This not just a case of “they did A, so we will respond with B”. It's a case of “they did A, B, C, etc. so we are responding with X after 10+ years“. To be fair, successive US administrations across party lines gave CCP a long enough rope.
It’s the same, reactionary logic, that fails to give first concern for the desired end state. Delaying reactionary measures is what many call patience.