It's nice that they're doing this, helps advance the art I think. But it also puts a lot of smaller operations in unis sort of under the Google system in that they're best compared to Google's ML work and others using these datasets. It's a small way of stacking the deck to make Google and DeepMind more embedded in the community.
That said, its utility for others surely outweighs the strategic advantage gained here, so I for one welcome these libraries. A lot of work goes into them. Hopefully others will release theirs as well.