Ask yourself this question, 'Would you rather a book be too short, or too long?'

Some stories work better in a short format. e.g. Sherlock Holmes, while short, feel perfect for the stories being told. I really don't think I would like some Tom Clancy sized novel with Holmes and Watson. For me personally, there's nothing worse than a book which feels as though the author added in lots of filler to hit a page count.