I strongly agree with the outcome but the cost in the other direction is good API design is a creative process. If you sit down and design a kick-ass API for a year, another person who re-implements is inheriting that design, and its benefits, for free. I do wonder if another case will wind its way up one day where the defendant lifted the API not for interoperability but because it was a clean or clever interface. (Seems a bit far fetched but would round out fair use further I think.)
The majority opinion cited precedent (Feist) that copyright is not intended to profit the creator. It's to advance the progress of arts and sciences. If someone copies your amazing API, that sucks for you, but it's not stopping the progress of arts and sciences.
Yes fair point I misread the OP that they were strictly talking about the legal tradeoffs. I was more thinking what was the actual cost to creators under this version of fair use.
They kind of intentionally danced around that question with 'are APIs copyrightable'.
Because here it's allowable for a product that isn't competing, and is being leveraged for interoperability/ease of users to adopt (rather than for how clean/clever it is).
What if someone had copied Stripe early on, though? Stripe's big claim at launch was "payment processing in 7 lines of Javascript" or similar. Obviously there were other barriers to entry, but what if someone else entered the market at that time with a similar (or even identical) interface? That question was left unanswered.
Even if that happens, we'll still get beautiful APIs made. Copyright is a means to an end. Fonts, for example, are not subject to copyright, but we still see beautiful typefaces made.
