Wow. Now you got me wondering what's so great about the new UI that you would sacrifice a jailbreak? I like the new calendar but what else is different from 7.0.x? Not that I'm upgrading, just curious. I don't think I can live without a jailbreak.
I felt they did a lot of trimming with the way it looks. I'm a big fan of the minimalistic style these days. I did have a jailbreak 3GS with iOS 4 and it was nice but I never got too heavy into the features aside from changing the font style. Even when I had an Galaxy S4 I didn't do much but change font style. I just never really get into customizing my phone like that outside of what they already give me.
However I have been reading jailbreak threads and some of the stuff now is pretty dope like that picture in picture video that android has you can get on a jailbreak which is amazing. Other than that I don't know too much about it to begin with.
A lot of it has to do with the visual appeal and the other portion is being afraid to "break out the shell" when it comes to adding some personal customization.