The principles of the OSR are...
Steal other peoples works and slap your name on it with sometimes only superficial tweaks while using the d20 SRD/OGL as an excuse.
Back at the origin of the OSR, I had problems with the retro-clone craze too, basically for the same reason. I got the value of C&C doing AD&D 3e, but OSRIC seemed to be exactly that idea of "stealing" Gary & Dave's work.
I wasn't a fan of the idea, especially because AD&D books were easy to find on eBay, but I didn't grasp the yearning of many people to write (and read) "TSR compatible" stuff until I joined up with Knockspell and Fight On! magazines.
Also, I saw that the OSR world was swiftly moving beyond retroclones to include very original works using the old mechanics. Of course, we still see new clones like Old School Essentials (OSE) and others, but I think that's because there is an audience for New Books + New Art + Old Rules that's willing to spend.
Plus, there's the old chestnut of "Amateurs borrow. Professionals steal."