It seems disingenuous to write an article extolling the benefits of JIT and self-modifying code without mentioning the security concerns of allowing anyone to change executable code.
You don't need to be able to change code to execute arbitrary code --- see return-oriented programming. Besides, NX gives you almost all the same benefits.
Restrictions on code execution strike me more as business controls (and yes, assaults on freedom) than real security measures.
