Definitely agree with you that the result of these experiments and others similar to it so far have produced unstructured and unenjoyable music, when compared to human-level compositions. I also agree that you could achieve similar results by some rule-based system involving random walks through a musical scale, common chord progressions, etc.
However, to me what's exciting about this and similar projects is that the network is learning these rules on it's own. The whole point of machine learning is that we don't have to explicitly state or even understand the underlying structure or music theory, because the algorithm figures it out on it's own. And sure, right now, it is only learning structure that we can codify manually in rules. But who's to say that as neural network techniques become more advanced, they won't be able to learn more abstract concepts such as the overarching dramatic structure of a musical piece?