Knowing about a bug and knowing how to fix it are two completely different things. For example Apple knows there's a problem with Wifi in iOS 8,'but if they knew how to fix it, it would have been fixed in iOS 8.0.1/2 and Apple engineering wouldn't have their senior support advisors reaching out to customers (like me) to get logging data on the problem.
I'm a software developer (not iOS) and I've never once had a problem with having too much data about a problem. Usually it's the opposite.
As for iOS 8, basically it was a complete overhaul of iOS and they only had 5 months to do it. Apple has no automated test tools. All testing is done by hand. It's a wonder iOS 8 even runs at all.
... and you know this how?