Most of the iOS ui SpringBoard bugs are due to them rewriting the codes in Swift. Many Autolayout bug. Music app can’t even align the play button at center. Also Craig Federighi is busy with Siri, and busy shooting down Note 8 in social media. I was annoyed when the text replacement bug took one beta to solve, where the Calculator bug took 5 or 6 releases to solve. And the third reason is they expect users will actively test iOS for them. With so many bugs surfaced in media and in released version, my guess is no one is telling them the bugs during beta. Another reason is iPhone X is iPhone fragmentation with different home screen UI. You’re are right this will introduce complexity to the code base. I’m thankful for the touchbar in MacBook Pro and the notch design in X, both I dislike. This make me realise the many good points in other platform. Sort of like bursting my Apple fanboy bubble.

Curious to know more about your claim that rewriting stuff in Swift causes a lot of bugs - got any sources on that?

Rewriting any mostly-working code in any language—even the exact same language—causes bugs.

It’s been that way since the 1960s.

It “has to be done” sometimes, but put that day off as long as possible.

That makes sense I suppose.

Seems improbable to happen right now; there isn't really a large amount of newly-added complexity. Compare to QA in the beginning of the iCloud Document Sync (Ubiquity) era, where every app and many parts of both iOS and macOS had new features: Ubiquity itself broke down frequently, but the QA and maintenance engineering going into it didn't seem to make anything else in those releases less solid.

You could go slower like everyone else.. with less features..

I believe in general those using devices would always trade security for convenience and new, flashy features.