Most iOS updates are smooth and trouble free. Still the far best mobile platform in terms of actually receiving software updates and new features. In the case of iOS 11 I would guess all the software changes required for the iPhone X has caused a temporary a dip in quality. I don't think it's representative of the quality of iOS updates overall. Things could be a little bit rocky going forward though as Apple will continue support pre-iPhone X era hardware for the next 3-5 years. I believe this is the first time they've had to support two distinctively different flavors of iOS UI in this way at least since the iOS6->7 days.
I agree — I’m not in the “Apple software is going to hell camp”
But the fact is, you can ship glitchy software and fix it later, so they do. Hardware is much more expensive to do that with, so they don’t.
IMO it’s less “focus” and more having to rely on third party manufacturers who will push back due to liability.
iOS 11 is a beta quality product. One org that I’m familiar with has a 5x increase in help desk calls and replacements, mostly around the voice phone components failing.