My understanding is roughly: the settlement amount should be thought of as $n per song that they actually intend to litigate, not $n per song that was available for download, which at least seems like a coherent position to me.
The numbers still seem not particularly unreasonable in that context, but are certainly more than $4/song.
It's frankly bizarre to say "the plaintiff would have been ethical to offer to settle for $90,000, but unethical to offer to settle for $9,000."
This seems to be the entire point of a settlement offer. "I think I could get more out of you, but we can both avoid the court costs if you pay me less than what a court would award me."
I think the argument is "if someone offers to settle for $9000, they lose the right to sue for more than $90,000." Which gets rid of the entire concept of settlement offers, but it's the best I can come up with.
The ethics of the matter is frankly tangential to the original point, massive amounts of money per little tiny chunk of data (be it song, or sms), is nothing new.
Anyway, this is probably pointless, but I'll give this another shot: Yes, the entire point of the settlement is "I think I could get more out of you, but we can both avoid the court costs if you pay me less than what a court would award me."
The "[what] I think I could get you [for]", in the case a few dozen songs. They think they can absolutely ruin you for a few dozen songs, so they are offering you a settlement of several thousand dollars. For our purposes, this is effectively a settlement of hundreds of dollars per song.
Ethics comes into this as a tangent in that I think, if they correctly labeled the settlement, people would not have stood for it. In doing it the way that they did they paint a (in my opinion crap) narrative of being reasonable.
Regardless, massive amounts of money for single SMS messages/songs should by no means be surprising. Even ignoring the pre-litigation letters situation entirely, they were being awarded ludicrous amounts of money for individual songs.
The numbers still seem not particularly unreasonable in that context, but are certainly more than $4/song.