I noticed, in recent months, that many Google sites don't do this anymore. The site simply fail without giving any reason.
Worse, even for some Google sites that never required js, but now ceased working. Google translate, Google image search, are 2 examples i recently experienced. (but i haven't done detailed investigation)
So what does this mean? some quick thoughts:
② Google of course relies on dynamic web to survive, thus js. They, for political reasons, must push js, and HTML5. Vast majority of their product, their bread n butter, depends on js. So, the gesture of simply dropping error messages for non-js browser is a reflection of this.