That seems fairly straightforward, but there must be some point in history where that was abandoned. Southern states were party to numerous suits during the civil rights era, and those cases always went through lower federal courts. And the lawsuits states are filing concerning Obamacare will be filed in lower courts.
It might be that the volume of such cases made it impractical for the SCOTUS to handle them all. And also, what system of federal courts existed when the constitution was written?
That is probably why that section was included. The states wanted to prevent the Federal Government from using the Judiciary as a hammer to attack State Sovereignty.
Arizona should raise the issue now that the Circuit Court had no jurisdiction to make the ruling it did and it should ignore the decision and continue to enforce the law.
The Constitution could not be clearer, but then who the hell bothers to read the constitution any more? Certainly the Federal judiciary has no interest in reading our founding documents.
“It might be that the volume of such cases made it impractical for the SCOTUS to handle them all”
Then they should have amended the Constitution.