As a product gains complexity, things are more likely to go wrong. It isn't a case of incompetence.
That's why there is something called beta testing. It is so the software can grow while the users don't have to deal with those things going wrong. It means scrutinizing the software and fixing
every issue you can discover to make the users deal with as little issues as possible.
It's not incompetence, but it can easily be laziness with lack of testing. It seems like Apple tried to let the users do the beta testing instead and they may have done less quality testing of their own. The public releases of 7.0, 8.0, and 9.0 have felt like public betas, but 5.0 and 6.0 weren't like that. They may have had some issues, but they were small, and not close to showstoppers.
Since 7.0, Apple have released an X.0.1 update only a week after the X.0.0 update. It wasn't like that before 7.0 because they didn't rush the big update out the door and fix the known issues soon after. They made a solid X.0 release and fixed issues when they popped up, and it took more time because not many issues actually would pop up.
4.0.1 came out a month after 4.0. 4.0.2 took another month.
5.0.1 came out a month after 5.0. 5.0.2 only fixed one issue on the iPhone 4s.
6.0.1 came out a month after 6.0. 6.0.2 took more than a month after 6.0.1.
7.0.1 came out a day after 7.0. 7.0.2 followed a week after. That went all the way to 7.0.6.
8.0.1 came out a week after 8.0. It destroyed the iPhone 6 baseband firmware, and 8.0.2 came out 2 days later to fix that. Then 8.1 after only a few more weeks. That went to 8.4, the first iOS version to reach X.4.
9.0.1 came out a week after 9.0, and 9.0.2 came out another week later. Then 9.1 after a few weeks. Now 9.2 is already in beta, within 2 months of 9.0.
Before iOS 8, Apple only needed to do an X.1 update around 4 to 6 months after the initial version. Now they do it in one month. Someone would say in theory that many frequent updates would actually help, but that's not the case. They are a sign that the software still needs work. I'm tired of seeing people say X.0 releases have always been this way because it's not true. 6.1 wasn't a major patch for 6.0 like 7.1 was for 7.0.
Simply put, if it really was about growing complexity, it would have always been a problem. It wasn't a problem before iOS 6, and I'm not talking about services like Maps. The functionality of the device itself wasn't the problem then that it is now.
If you want to say Maps was iOS 6's functionality issue, I would respond with iCloud Photo Library, which would fail to upload, fail to download. and simply not work. They released iCloud Photo Library and slapped a beta tag as a disclaimer in case your photo library got destroyed. That was after they already delayed it.
I shouldn't have to lower my expectations of Apple.