Unless someone starts paying people to read a system like this will probably be inevitable in our information saturated age were nobody has the time to read anymore. Pulling in decades or centuries worth of context and motivation for the passage you are reading is definitely a worthwhile goal. I really like the layout of the reimagined wikipedia it has the feeling that there is an entire group of people and subjects…
And yet, it somehow feels different. It's really as you say, "it has the feeling that there is an entire group of people and subjects the care about and rely on the central topic"; those thumbnails beckon, invite you to explore in a way that regular hyperlinks don't.
(That, or maybe after years of getting stuck on Wikipedia, recursively reading linked pages for hours on end, I eventually grew desensitized to regular links.)