[Matt Flynn]

in the case of no-limit hold 'em:

1. there's a ton of "basic" stuff that isn't in print
2. the market is presumably small for such books
3. there aren't many people that are good enough to write one AND are sufficiently motivated to get the writing done AND can write reasonably well or find someone to do it for them.

however, i think easier-to-write versions will be out in the coming year or two - primarily hand example books.

also, motivation is interesting. there isn't enough money in books to outweigh a high-paying job or a skilled player's earn rate, assuming that person liked to play. interest or ego or something else has to motivate you.