An interesting question of 21st century science is, whether it makes sense to still invest time to write books? Some parts of science have essentially abandoned book writing already. The literature moves almost on a weekly pace in some areas. Maybe even having to look for daily updates in some large-scale laboratory-driven world-wide competitions will be our future. How can it be even reasonable to consider sitting down for multiple years to write a single book? In fact, it could actually be a practical method to deal with some madness.
After all, the scientific endeavor aims to generate long-lasting insight, which is useful not only today, not only tomorrow, but for generations. So there has to be a balance between pushing far beyond the frontier and trying to solidify the frontier itself. Neither extreme approach is going to get us very far. If one just latches out and tries to find hidden gems, the failure rate will be far too high, and one has to probably repeat the process many times to actually have solid knowledge. Just building a solid smooth frontier is also not going to cut it, the innovation level and progress are just too slow. Although it may not look like it, book writing can actually be an excellent way to balance the necessary processes in research.
From my personal experience, I found switching between writing a book (be it a monograph or a textbook) to thinking about research questions a very practical solution. In fact, it can be very frustrating if for several weeks one does not make progress towards a research idea. The thought process narrows down until it is almost impossible to make progress. If one then switches to writing a book, which organizes the results near the current frontier, one is bound to make progress. This yields new motivation and also provides additional insight into current techniques. Then one can use the additional motivation and new techniques to go back to the original research problem. In addition, book writing also indicates, where the gaps in our knowledge frontier are. Thereby, it provides a neat way to find new exciting problems. The interplay between the process of leaping out into the unknown and pushing/polishing the immediate knowledge frontier can lead to a positive feedback loop as shown in the figure below.
One may also view writing a book as a systematic procedure to carry out a scientific version of checks-and-balances. If a field is strictly dominated by hunting for the next large jump, then it can be difficult to systematically reproduce past results. This means a solid foundation is at least partially missing. Stories and concerns about results, which are not reproducible, are certainly available in the scientific literature as shown by just the following examples: click here, here, here, or here.
Never trying to aim high is probably equally as detrimental to a scientific field, progress is bound to asymptotically crawl to a halt. Creative new ideas are discarded as too much out-there by the vast majority in the field. This makes it difficult, if not impossible, to speculate on big ideas. Books tend to generate a broader perspective, they show us much more clearly, what we really know, what we just think we know, and what we may dream about.
In summary, if you ever thought about writing a book yourself, I would recommend giving it a try if certain conditions are met. The main hint is: Planning ahead is key. It will never be finished in the time you calculated initially, and it might be out-dated, or out-competed, if planned incorrectly. Hence, you should probably only try it if you really enjoy it, and if you do not plan to depend upon it in any way. If these conditions are met, I personally think it is a very important experience, and a book can still make major contributions to the general scientific endeavour.