This is the same logic that keeps me from jailbreaking my iPhone - it's possible and fairly straightforward, but eventually some condition (likely an important iOS point release) causes the situation to revert.
f.lux for iOS is tempting me to re-visit this, as it's crucial to me getting a few more Z's at night.
Meanwhile I've been enjoying a jailbroken iPhone for over three years now. How many important iOS updates have there been anyway? All I can recall were the SMS exploit and the PDF exploit for which there was a fix available on Cydia sooner than Apple provided an iOS update.
f.lux for iOS is tempting me to re-visit this, as it's crucial to me getting a few more Z's at night.