I think that properly done, theory is the body of thought that encapsulates craft (i.e. "I am doing this and these are the general rules that apply to it.")
The problem with RPG Theory, per se, is that, almost always, it is mired, strongly, in identity politics. This makes producing a taxonomy of "what we do" very, very difficult. It means that when we distill theory from a body of craft there is, almost always, inherent biases that damage the taxonomy/predictive ability in some way.
As a result, the discussions of pure craft seem to me to be more useful than most discussions of theory.
-Marco