IBM wanted companies to embrace SQL - because then people implement applications already compatible with their database product, and conceptually could migrate without rewriting their applications.
Amazon wanted companies to embrace S3 - for the same reason. Or maybe they didn't, but they decided that the API was the least significant compelling part of their product - that people would still choose S3 regardless of whether other storage offerings had the same API - for the cost, and durability.
Sun wanted Google to use Java. Because more developers using the language, regardless of the underlying implementation is better for the entire ecosystem.
Oracle doesn't.
So to some degree i do feel like consent matters here. It doesn't matter if Oracle copied Amazon's S3 API illegally if Amazon doesn't care enough to pursue it.
Finally, I hate arguments that say "It's just the API". We all know a good API makes or breaks developer tools.
Ultimately, I feel like it goes without question that a decision in Oracle's favour will cause irrevocable damage to the industry and permit all sorts of bad actors to start looking to purchase ownership to APIs just so they could sue those they consider infringers.
But I can't help but feel that ultimately Oracle has a point :(