From my perspective, the first test for any article in Wikipedia should be... is it useful.  If it's not useful, why do we have it?  In terms of inclusion criteria, I believe there are many attributable sources on these chess openings as more books have been written about chess than any other sport.  The openings also serve a historic purpose, as they were developed quite some time ago.  I do recall reading that a test for inclusion in general is, "Will anyone want to know about this subject in ten years".  In the case of chess, I believe many people will be interested to know about these openings in ten years as we are looking at openings that are well over 10 years of age in many cases.