Like Gothicangel, I am not sure large books have ever left us. I think it depends on the genre you read within. The article itself was pretty generic, IMHO, but I did like the writers take on are large books worth the investment...
Just as long as they repay us. Reading through 800 pages or so raises expectations in a way other reading doesn't come close to. All that time given to a book - it had better be more than a gimmick, a trick, a post-modern conceit. It had better be a story we haven't heard before, or already read in another version. It had better change us, make us different to how we were when we started - make us bigger, somehow, ourselves.