I am in the other side, I love my Jailbroken phone, it can do so much more for me. Jailbraking is not a must for everyone, if you are 100% happy with stock, there you go, for me the stock firmware is capped too much for my likeness.
I want to have custom ringtones for SMS and Email, I cannot live without SBsettings which in turn allow me to have even better battery life (since i can enable/disable pretty much anything with one click). I can leave my External HD at home since I got 6GB available on my pocket and i can use it as USB HD.
I am playing my old GBA roms which I love (Mario 3, zelda), SMS quick reply is also a must for me.
Being able to storage, email and view any type of file (besides stocks PDF, and office, i can Email, databases, zips, gzips, xmls, png, etc).
All that make my phone complete (to me, totally personal preference). again if you feel your phone and ipad cover all aspect of your life, then enjoy your stock phone
