Well-meaning friends and relatives often ask me why it is that we academics have such a loathing for writing useful books and articles. Why is it that there isn't a literature that is both (i) academically respectable and (ii) useful or entertaining or enlightening to normal people? This is a serious question and it deserves a serious answer. So let me try to answer this excellent question by describing something about primate behavior.
As anyone who has been around monkeys and apes knows, primates organize their societies around dominant males. Normally, the procedure for determining which male gets to dominate is that all adults show one another their male organs, and whichever male has the biggest one wins. (This is why it's called social organ-ization.)
This “primative” technique worked well as long as apes lived in warm climates, but when they moved into northern Eurasia and over to places like Canada, the risk of frostbite (which was especially severe for the most promising candidates for leadership) necessitated ritualized substitutions for the organ-display. One of the first substitutions to be discovered was war. Eventually, most apes came to believe that it was far more civilized to kill one another and burn down one another's towns than to show each other their waterspouts. That's why people who do the latter are put in jail, while those who do the former are given medals.
During the reign of King Henry VIII of England, men got into the habit of wearing a large amount of stuffing in the crotches of their breeches. The resulting bulge was meant to suggest one's qualifications to be dominant male in a tribe of apes. This device was called a cod piece, perhaps because many female apes quickly learned that there was something fishy about the apparently impressive credentials of the chief apes of the day.
During the Tudor and Stuart period in Merry Old England, the fashion of wearing a cod piece (or a CP as it was called) caught on even among professors at Oxford and Cambridge. Their custom was to wad up one offprint of each book and article they had authored and to stuff these offprints into their trousers. Whoever had written the largest number of pages ended up with the most prominent CP and became principal primate.
It was during the Principality of the legendary Dens Lepus (known informally as the Rabbit-toothed Doctor) that the custom of the academic CP took the form that it has to this very day. Dens Lepus noted that the invention of the zipper made the traditional CP rather awkward, since one's credentials tended to fall out onto the ground whenever his fly came undone. So the hare-toothed doctor suggested that people just list the titles and page-lengths of all their publications on several sheets of foolscap and show these to one another. (One of the unexpected benefits of Dens Lepus's innovative changes, incidentally, was that it allowed women to enter the competition for the first time.) Owing to his prominent front teeth, Dens Lepus's lips could not meet to make the sound of the letter P, so his awkward efforts to pronounce CP ended up as CV. So as to avoid embarrassing the good doctor, academics have referred to their ersatz cod pieces as CV's ever since. But the devices are still used to determine who is the biggest monkey.
Now the rules of CV-ship are quite complex. In general, whoever has the biggest one wins, but there are only certain things that add to the size of one's CV. Obviously, e-mail messages make no contribution at all to CV tumescence. Neither does being an effective teacher in the classroom, or being generous with one's time outside the classroom. Nor, for that matter, does being a decent human being whose example students could follow to their benefit. The only thing that makes one's CV big and impressive is writing lots of pages and having them printed on dead trees. But even though writing is the only thing that adds weight to one's academic cod piece, not all writing counts. Nothing that is commercial counts, nor does anything that is interesting or useful or educational to the general public.
The reason there are so few books and articles that are both academically respectful and useful or interesting is that the categories are defined so as to be mutually exclusive. An article is fit for academic publication only if it puts a reader to sleep before the end of the first paragraph. And if the article succeeds in inducing a coma in the reader, it is bound to earn the author a prize. (Prizes, by the way, add bulk to one's CV.) For this reason, university mathematicians are not likely to get much academic merit for writing books that merely help people improve their arithmetic. Philosophers are not likely to get much credit for writing books that merely help people think interesting ideas. And scholars in religious studies would probably get negative credit if any of their writings brought anyone closer to God or nirvana.
I'm sorry if my grasshopper logic sounds harsh to my primate friends, but please don't forget that we members of the Acrididae family have been receiving very poor press among primates ever since a Greek fabulist named Aesop compared us unfavorably with ants. (That piece of muckraking entomology was such an outrage! I mean, have you ever smelled an ant? But I refuse to stoop to the level of these ridiculously articulated mephitic monstrosities of nature by telling you every unpleasant thing I know about our formic cousins.)