Hi Tomas.
I brought the thread to our attention because I remember another conversation with DocJames,
who had a very important point stating that Wikipedia Zero could be the way where millions of people can access scientific literature, via Wikipedia.
Wikipedia Zero is a project by WMF to give access for free to Wikipedia via mobile devices, all around the world, expecially in the "global south".
Now, I don't really know if pictures in Wikipedia articles are visible with Wikipedia Zero, of if they would be in the near future: but in that case,
PDFs stored on Commons could be the same thing.
The viewer could allow users to access sceintific articles for free, directly.
Aubrey