My opinion is that APIs should NOT be copyrightable under any circumstances, because they are the essence of today's app ecosystem and rich internet services. Practically every application you use today makes some API calls, whether it is to display your timeline, or to to render your GUI window etc. Now, if APIs were to be allowed to fail under copyright, then you could potentially have a situation where if a service wants to block certain competitors from effectively using their APIs, they may be able to do that now under the pre-text of copyright.
Imagine if now, you could not import playlists from a competing application, because now they are able to claim copyright on certain parts of it their API you may need and target you specifically. End result? You application will be less competitive in the marketplace and you may fail, even if you product is very good.
This issue gets even worse with programming languages, because for example many of the dynamic ones have a print() function. Let's say that one of them was able to now claim as their own creation that fails under copyright.
Can you imagine what a headache that would be for the other languages?
Also, probably a lot of music services, have a function, such as 'play()', what if one was able to claim copyright on it, forcing others to change their function to '__i_am_a_very_silly-play()' in order to avoid infringement, making their API less intuitive to work with for the developers, therefore resulting in less apps for their particular service and therefore less market value, even if their service is as good, if not better than those who was able to claim copyright on 'play()'? I am not even talking about breaking all the apps that use the older 'play()' etc. etc.
Now, some may argue that perhaps a more specific form of API should be copyrightable, such as the Java API, but in reality, every programming language under the sun has a somewhat similar API, because quite frankly, they are not all that different in their fundamentals and if you independently came up with YOUR OWN implementation of Java, that does not infringe on anything, but its API-compatible, than you're smart and should not be punished for it.
Also, Android really helped Java to get out of the enterprise spectrum and back into the public view, so there's that aspect of it.
However, I am not familiar with all the specifics of this particular case and so my opinions should just be taken for what their are - opinions, not facts.