Note what this (or any) NSL does not request, for good or ill given the explosion in digital communications since Smith v Maryland in 1979 and subsequent case law (which effectively says that metadata, as "business records" provided to a third party, do not have an expectation of privacy and are not covered by the Fourth Amendment): CONTENT of communications.
Note what is also missing here: the target. People assume it's an innocent US Person. The fact is, if a NSL is used, the person is almost certainly a foreign intelligence target under active investigation, and the reason why requests are "dropped" is because IF a NSL was used in the first place, we don't want to reveal any further sources, methods, or what we know.
Unless and until the Supreme Court of the United States speaks on this matter again -- and it very well may, and it very well may rule differently given how the communications landscape has changed in 35+ years -- that is the law of the land. Not peoples' opinions, not tech commentator know-it-alls, not self-proclaimed security experts.
If something doesn't legally require a warrant, it amounts to a formal request. I'm not saying it's always perfect execution, but the whole purpose of a NSL is so that it runs through its own legal process -- which, again, is for information that does NOT require a warrant. I know people think it has no oversight, but either something requires judicial oversight, or it doesn't. And NSLs DO have massive amounts of LEGAL oversight, just not a warrant signed by a judge -- repeating myself here -- because one isn't required for information sought by a NSL.
And like information that we seek under Intelligence Community authorities, we don't want the target of the collection or surveillance knowing we are targeting them, or where, or how. Yeah, it sucks, and it's imperfect, and all that, but even in a democratic society, you can't just say every single national security or intelligence issue has to be in the open. That's not how even democratic societies work, or can work, or should work, when it comes to national security matters. Some things tilt too far in one direction based on national events, or politics, etc. Then they tilt back. It's never fast enough for proponents or critics.
The main issue is that people say that something like a NSL is "bad" because it doesn't have judicial oversight in the form of a warrant. If the information sought doesn't legally require a warrant, I don't know what to tell them. Then when we do actual court orders and warrants when required for foreign intelligence collection, issued by the very court whose sole purpose is to protect the rights of Americans under the law and Constitution in the context of foreign intelligence collection, they complain because the evidence is heard and rulings are issued in secret.
A NSL at its core is nothing more than a formal process and notification, with a lot of other legal considerations surrounding it, that is the equivalent of someone saying, "Hey, can you help us out...and oh, by the way, here's a bunch of other legal crap which justifies this. And don't tell anyone, because this is a national security issue." I understand why people make an issue of it, because they'll say, ok, even if it's used for all "bad guys" it still "could be abused". Uh, and? Any government power at all "can be abused". Secret ones "can be abused" in secret.
And yet, the government still has to have powers, and some of them on the national security and intelligence side are necessarily cloaked in secrecy. And in the conduct of war, diplomacy, law enforcement, and counterterrorism as the United States, with our myriad interests at home and abroad, we do all of these things for a reason. No, it's never perfect, and it never will be. People act surprised when the use of something like NSLs skyrockets since the late 90s...well, guess what else skyrocketed since the late 90s? The goddamned internet, which we invented, and our enemies are literally using it against us. No, not bullshit like tweets and Facebook pages; adversaries using the internet for no-shit coordination, collaboration, and C2. AND intentionally using US systems and services because they know that it's a legal rat's nest for us to get to them there, even if they're non-US Persons outside the US.
So anyway, yeah, it sucks, but the general attitude most people in the national security and intelligence communities are operating under is we had better be using the full extent of the capabilities afforded to us under the law, and we don't make the law.
The other issue, speaking broadly, is that sometimes the target itself is not subject to Constitutional protections at all, because the target is a non-US Person outside the US, and it is absurd to argue that if said target's communications touches the US in any way, suddenly it should be subject to Constitutional and warrant protections, because warrantless efforts to obtain it otherwise "could be abused".
SCOTUS can either speak to it, or Congress can pass a law. My own PERSONAL opinion, in a vacuum, and absent everything else I know, is that metadata should be protected -- because of 1.) the explosion in digital communication and the internet in the ensuing decades, combined with 2.) government's ability to exploit large amounts of collected data because of advancements in technology.
I would point out that even though portions of the statute with regard to NSLs have been found unconstitutional, it has only been about the gag order and length of time, not the use of a NSL, which is essentially a formal letter.
The issue of who the Constitution protects and where has many different arguments, but in a traditional law enforcement/intelligence/national security context, generally we see it as protecting either 1.) US Persons (be they citizens, permanent residents, lawful visitors, groups of the above, etc.) or 2.) people IN the US, no matter who they are.
The FISA Amendments Act shifted this a bit due to the reality that over 70% of international internet traffic touches the US somehow, by design or incidentally, and we had an absurd situation where both ends of a conversation would be AQAP members outside the US, who are not US citizens, and have never been in the US, who we suddenly can't collect on, even with capabilities outside the US, because one of them is using Hotmail.
If Constitutional protections applied to everyone, everywhere, my view is that the concept of borders and nation-states is meaningless, and it also destroys foreign intelligence collection -- and I mean Destroys. That said, we can certainly argue that we want to follow Constitutional *principles*, and aside from things people want to cherry pick that they don't like, I would say that, generally speaking, we do that.