If you pull back from the granular debate and think about it, none of the FISA justifications align with reality.

The FISA system is a designated secret court system that is said to only pertain to "foreign nationals."

Ok, so if we accept the premise.  Foreign nationals do not have U.S. constitutional protection.  So why does the surveillance and intercept of them require secret U.S. courts?  

In reality, the Secret Courts are needed because it's not foreign nationals that need to be navigated in the surveillance system; it's the American citizenry engagement within that surveillance that requires a different legal approach.

Why should an American citizen suddenly have their constitutional protections switched from U.S. Federal Court, to U.S. Federal FISA courts (secret), simply because their contact -perhaps inadvertent- skims up against a foreign national?

The constitutional protection (4th amendment) should not be arbitrary, depending on your contact.  A regular federal court judge can decide on the issue of a Title-1 warrant, that can be filed under seal if the exploration of the contact is a genuine concern.

There is no need for a secret court for either foreign nationals or U.S citizens.  The former do not have constitutional protection, and the latter should not lose it under arbitrary determinations of U.S govt officials.  

That's the entire predicate that underpins the 4th amendment.

All of that said.... I'll tell you why this issue is so important, and it has to do with the future, not the past.

The justification for the FISA-702 warrantless searching of American metadata, is a cornerstone for the enlargement of a surveillance state.  The flawed precept behind 702 specifically, is the gateway needed to expand the system.

Real ID, Digital ID, AI used in facial recognition systems, and the larger issue of track and trace capability of U.S. citizen data (connecting your physical identity to a digital fingerprint), requires some legal justification to create a surveillance network DESPITE the 4th amendment.

FISA-702 is the proverbial camel's nose under the tent of privacy.  

IF we were to abolish FISA-702, which we should, then what legal justification would exist to continue unsecuring the American people from "their private papers and effects."  

The build out of the surveillance state becomes more legally tenuous, perhaps impossible, if privacy protections of the 4th amendment are firm.

Finding a way to surveil Americans, while working around the constitutional protection in place to stop it, is why the FISA-702 issue has become more important for those who are building the surveillance system under the guise of national security.

Challenge the legal justification for FISA-702, and you throw a massive wrench in the machinery of a growing surveillance state.

If you are secure in your papers and effects, you cannot be forced to "show your papers."  

Right now, the monitoring system designed is being done so they can get the answers to your identity, without having to ask you to show your papers, which is unconstitutional.

You drive through the metaphorical checkpoint, because the system automatically recognizes your identity.  This is said to be a legal workaround. 

However, what happens at the checkpoint (bank, atm machine, employment verification, port of entry or even voting booth) when government identifies you (for whatever arbitrary reason they construct) as a "politically exposed person."