There's a reason for that. I am not a lawyer but I have had dealings in US District Court as a plaintiff in a civil suit against the Federal government. As it was explained to me by my lawyer at the time, a magistrate cannot hear a case. There's a little trick they do when a judge is first assigned to a case. They call both parties in before a magistrate. This meeting is held in private in the magistrates chambers and he (the magistrate) does his damnedest to get the parties to settle before the time and expense of a trial. During that meeting he offers his candid, and hence off the record, opinion on the case. In my case the magistrate told the US Attorney that there was no way he could see the judge ruling in their favor. They settled then and there. I suspect that this was a similar meeting. They need to hang tough and get before a judge.
I too want to see the states have their day in court.
IMHO "Interstate Commerce" has been abused over and over by the federal government.