i agree, i dont think apple is too concerned with people exploring the iphones capability... however, you must note that many of the decisions they make pertain to their exclusive contract with provider att... and, coming from att's shoes, though some decisions they make are stupid, i can understand why...
what most people don't know? att helped develop the iphone in partnership with apple, and spent over 1.5 milion of their own dollars investing in the development process... as far as jailbreaking is concerned, rumor has it that apple is working on developing ways to detect software hacking, as well as the "health" of the iphone... for example, if the phone has been dropped, how many times has it been dropped, has the case been opened, etc etc... with the amount of people hacking/breaking/obtaining new phones, apple really has no choice...
p.s. jailbeaking is good but greatly affects the performance of the phone...