Because what is being contemplated by the USA isn't a return to former days.  Rather they wish us to keep our markets open while closing theirs.  If that's truly what they are asking for, then the only valid response is to close our market as well, but I truly don't think either their side or our side understands the complete implications as of yet.  No doubt it will be painful and disruptive to both sides, and collectively North America would lose to Asia and Europe if that is the outcome.