When talking with people about academia and metrics for success, the adage "publish or perish" is often brought up. Even people far removed from academia seem to have heard it. However, simply publishing doesn't guarantee success, nor is it the only route to success.
Lesson 2: Academia is a lot more complicated than "publish or perish"
Tenure-track professors need to publish in order to remain competitive for tenure and promotion - and this record of publication typically journal articles. In many fields, books are not highly valued and the reward for undertaking such a large project may not be commensurate with the resources required for its successful completion. Furthermore, at research universities, publishing is only part of the equation: obtaining grants for projects is becoming increasingly viewed as vital to one's career.
Of course, more prestigious journals are valued more than lower-quality journals (though relative merits of journals can be debated). Furthermore, federal grants are typically viewed as more prestigious than state grants and other funding sources because of their perceived competitiveness (even though dollars are dollars, they look better when coming from the federal government). In both grants and publishing, original research that expands knowledge in the field is valued while other ends (such as teaching or service) are not as valued.
While there has been a movement in some places to emphasize the importance of the teaching and service, original research dominates the focus for traditional professors. There are other types of professors (non-tenure track, often with a name like "clinical professor" in many fields) whose duties are dramatically different, often with a decreased emphasis on original research to afford more time for other important activities.
What "publish or perish" comes down to is doing your job well and ensuring that those that make hiring and promotion decisions know it.