The original Java license mandates that mobile usage is differently licensed. Google basically writhed their own JVM just to bypass this - not for any other technical reasons.
You're begging the question. This Supreme Court fight is over whether a clean room reimplementation lets them do that legally.
And if it turns out that Google loses this case, then all sorts of things that we take for granted for interoperability (like WINE, and, before the MS acquisition, Mono) are actually copyright infringement and shouldn't exist. I don't think we can claim with a straight face that WINE or Mono were created with malice intended toward MS, so we should give Google the same courtesy.
And nowadays Android holds hostage any Java developer that wants to target Android, because one needs to constrain ourselves to Android Java's view of the world.