The key references section of a paper points to the most similar previous articles on the same topic that were extended, improved, challenged, or built upon by the paper. Key references allow the author of a research article to highlight the most closely related previous work in the specific topic of the paper. Key references are the natural complement of keywords.An interesting idea. If it is used (and taken seriously) by many authors it might help automated search systems identify important papers in the field.
On the other hand many journals require keywords and AMS classifications although I have rarely seen this information put to good use. For humans a well-written "Previous Work" section will have much greater value than just a list of references.
Key References won't become popular unless a major publisher requires them in their journal or conference articles. Would Key References play a useful role or just become one more thing authors have to do to get their papers published?