Which books do we like most? The ones which are smaller in size or ones that are very long. What about short stories? I guess there is no straight answer to all these. I have read short stories that are less than a page and I have also read books that were more than thousand pages and I have enjoyed both. Sometimes a writer can put across the point in few lines and sometimes the same point can be played out in hundreds of pages.
What matters in case of books is the content and way of writing. It is always possible to squeeze the whole concept of a book into few lines but a good book is not only telling you a summary of a story. It shows you a picture of era. The narrative is such that you can create cities, people, events in your imagination and to create that imagination, it requires for author to provide details and that takes a lot of pages. Sometimes the books also trace a lot of events which are important for the end result. If the reader were to read the end result directly it does not give the same pleasure of reading.
There are also books which come in many sequels and readers lap up all of them even if it runs into many volumes. In such cases, even though a particular book is short, the story is still long and a break in between increases the curiosity of the readers much more.
But I think there is initial inhibition in taking up a book if it is too long and heavy. Also if the reader is not regular or not reading the book in one sitting, they may lose the context and may never finish a long book. There is a sweet spot of 200-400 pages for most of the books and many authors try to not beat that sweet spot. In the end what matters is not the size but how the story has been put forward and how much the reader is able to relate to it.