Textbooks and research papers are an entirely separate topics, imho.
While it's easy to argue for textbooks to be openly available (just like education should be), there is no single reason for research papers not to be, since they purportedly advance science and human kind itself, and there is the demand of originality (if I can't access it, I can't establish if someone has not done it already).
While it's easy to argue for textbooks to be openly available (just like education should be), there is no single reason for research papers not to be, since they purportedly advance science and human kind itself, and there is the demand of originality (if I can't access it, I can't establish if someone has not done it already).