Personally, I'd much rather see them working on this than on Reader.
The justification behind shutting down Reader was the low number of people using it when compared to other Google projects, and the need to direct resources to other, more strategically important ones. As Larry Page eloquently put it, more wood behind fewer arrows.
So if Reader was sacrificed to the overarching Google strategy, it's at least interesting, and perhaps relevant, to weigh its loss against new projects that spring up, like this one.
Google has always retired products and always explored new avenues. I don't see the difference
I think your argument is still valid for something like Keep. I just don't think it is relevant here.
My comment is somewhat OT though so I'll kill it