You could also argue it's the difference between "dogmatic adherence" and "strategic application". At this point G+ is already integrated into all the major components of their platform. While I agree this is a good move, I don't necessarily see it as a step down. Requiring all new products to immediately integrate could be a major speed bump in development, so I can see how if G+ is not truly needed in the product, that it makes sense to allow for not requiring it.