Pretty much all software (whether that's apps, websites, programming languages, or anything else) past a certain complexity has quirks. Getting used to the quirks is part of learning the software.
Massively changing large swathes of your built-in software is bad for users! I get that it'd be suicide to say "OK, permanent feature freeze... now," but big changes to the UI on apps that are (to many normal users) fundamental to using Android break the user's understanding of their use, often amounting to months of acclimation down the drain.
It's very frustrating.