I agree with your observation that we should be thankful to anyone who is generous enough to provide any level of openness to their creative works. And its not just creative works. I see this generosity as a kind of sharing. I see this willingness to share as affecting lots of other aspects of society too. See Shareable for examples.
It's also great to hear how much students appreciate having course materials openly available on the web. I've looked at the example you gave - Nick Strobel's astronomy site. I totally agree that having astronomynotes.com available for free as a web site is great for students and I'm delighted to hear the quality is good too. This is worth celebrating and does represent a certain kind of openness and sharing.
Even though Nick's site is full copyright he offers it as a resource in astronomy education and encourages others to use it in their own astronomy courses or talks. That is generous.
Its also interesting to note whats in it for him. Whats in it for him includes:
- Attribution: He specifies the notice of authorship he requires others to use. (In my view this is highly valuable to Nick. In higher education citations and examples of pervasive global use are part of how your performance is measured)
- Money: Nick is offering his books for sale in hardcopy (unspecified amount) or as an e-book. The site says the e-book is cheaper than hardcopy - only about $55.60. Books are to ordered from McGraw Hill. (Supplementing your teaching salary with income from your course materials is certainly a practice that has been part of higher education for many years. If Nick teaches at a public institution and is paid by taxpayers to create his educational resources I think Nick should share them with the public.)
- Ownership Control - Nick's copyright notice specifies others should go to his site at www.astronomynotes.com for the updated and corrected version.
In Creative Commons lingo we might say Nick is using a CC BY-NC-ND license. NC meaning non-commercial (he retains commercial rights) and ND meaning he retains the rights to make changes.
There is nothing wrong with retaining these rights. However when I consider the educational potential of digital resources I see each of those as limitations. I think sometimes CC-BY is held out as the ideal license because it has the highest value and offers the greatest affordances for innovation - including pedagogical innovation.