I am thinking about Software Engineering researchers who never write software. I am thinking about Semantic Web researchers who have been building models and ontologies for ten years. I am thinking about Algorithm Design people who claim one algorithm is better than another, but they never bothered to implement it. I am thinking about Machine Learning researchers who never bother to test their schemes with the terabytes of data we find everywhere. All topics warrant research, but pure theory is not an acceptable methodology.
Daniel Lemire on Theory