Has the author looked at how GNNs are used in say predicting molecular properties[1] or molecule generation[2]? GNNs are the state of the art on those tasks and those problems are certainly much harder than the Cora/Citeseer/etc semisupervised node label prediction tasks.

[1] https://arxiv.org/abs/1704.01212

[2] http://proceedings.mlr.press/v80/jin18a/jin18a.pdf