Apple has always tweaked new UI designs over the first few OS releases.

They did it with Aqua when MacOS launched and again with the iPhone's original skeuomorphic UI and yet again with the flat redesign of iOS.

What they don’t do is open their keynotes with announcements of the tweaks. This isn’t like the other situations.

Of course. Every company does that. There is no company ever that just freezes after they release something.