Actually, jailbreaking still offers some solutions to two remaining issues - crappy notifications and the inability to share files between apps.
It's funny that people complain about such a minor UI design choice. Particularly since the iPhone notifications so closely resemble Growl ones. That seems like a rational, realistic reason to jailbreak. "I don't like the look of the bubbles."
What apps need to share files? Seriously. I've not once ever gone - hey, wait, if only I could get this into another app, curse you Apple! Like I want to shove my eBay settings into Tris or something. I suspect this "need" is actually fed by my original point re: illegitimate (and often pirated) software that doesn't behave the way it's supposed to and actually necessitates or is designed under the premise of files being shared or whatever. ("I need to be jailbroken because I use apps that operate in a jailbroken way.")