How much of that is because it's a one piece design? Supposedly BB machining isn't as critical on them as on a BB30.
Yes, one of the reasons more and more frame makers are going to PressFit 30 over BB30 is that the tolerances for the frame's bb shell aren't as critical to make for the proper fit. The nylon encased bearing assembly tends to stay quiet in the frame (unlike bb30) and there's no circlip involved like there is with bb30.
I'm not sure which models, but even Cannondale has gone to PressFit 30 over bb30 on some of their bikes.