Ask HN: A Wikipedia for books (ie, why isn't WikiSummaries more successful?)

I've recently been pondering the idea of a "Wikipedia for books" -- a site that houses a table of contents and synopses for every book. I would find something like this extremely useful, as there are many books that I either don't plan to read or not ready to read, but would like to get the general gist of, see the table of contents, get the main thrust of each chapter, etc. For most non-fiction books, this is enough to make me feel like I understand the argument the author is trying to make.

In researching this, I stumbled upon http://www.wikisummaries.org. It seems to be exactly what I'm looking for, except for one thing: it's not very popular and doesn't have any traction (to date it only seems to have 347 book summaries).

Wondering if anyone else would find this useful, and why you think this isn't more popular.