One thing very clear from the Apple iOS 8 release debacle is that some entity within Apple decided to release without the approval from the QA and Release team responsible for testing features and installation.
More surprising is how Apple had no immediate backup plan available to it's customers to conveniently roll-back to the previous iOS7 installed version.
This is very un-Apple like.
It's doubtful that the QA team would approve of a release with obvious product issues such as not being able to connect to a cellular network or Touch ID when those features are front-and-center and the core of what the iPhone does, and these issues were most likely known by the QA team beforehand, or, they were not aware of any late changes to the product that broke the features without the team having either 1) not enough unit testing by the dev team, or 2) not enough time to validate these changes were working properly.
Either way, the Apple/iOS QA team was put in a no-win situation and not capable of validating the product with a disorganized process, possible non-existent unit testing by the development team, and lack of patience in allowing the QA team to verify, to the fullest extent, the best possibility of a great release and identifying product risk.
The QA team knows more about your product than anyone else and has passion for customer satisfaction, pleasant user experience, and overall intuition about how the customer will interact with installation and product features. Listen to them and allow for the QA team to impact quality.