Totally agree. And I've written this in Apple user surveys, forums, and written their Twitter support about it. There are unintentional regressions all the time, bugs that didn't exist in older versions of iOS, that just get haphazardly released. Rolling back iOS version should be a fallback plan for those kinds of gamebreaking bugs.
Power management is a common area noted in the news, but I've also had an iPad Pro that just kept draining battery even when turned off via power switch shutdown, so that when a fully charged 100% device got turned back on, it'd be at 70% after a day, 40% after two, then 0%, without so much as a single charge. Not plugged into power, not touched or used. It was fine in iOS 13.4, then bad in iOS 13.5. Then later versions not playing from car speakers when connected to CarPlay on certain vehicles, requiring multiple unplugs and replugs. So many little bugs here and there that compromise the user experience, that pop up in one version of iOS, not present before. All together, the experience doesn't feel like "it just works."
So often, this kind of problem happens because the OS is so deep, and little feature adds and changes in the code can cause unintentional problems elsewhere. If it's a non-automated-testbed problem that doesn't cross the Apple QA folk's workflow or other employees' use case -- for example, employees never turning off their devices -- then it just gets released unnoticed.
Human error is understandable, but with no fallback to a previous iOS, it just hurts users that live outside the "typical" user/QA workflow.
(To make matters worse, Apple constantly tells developers to support two versions back when building & submitting an app to the App Store. It's so hypocritical when they won't even support two versions of iOS at the same time, pulling the plug so quickly on signing a previous version. It's just such an extreme reaction to security compromises and this whole "get on the latest" mindset.)
