In the old days, apps simply used the system color scheme. That allowed one to globally choose what they wanted. Now everyone has to implement light and dark “skinz.” Color me not impressed.
Users also expect prettier designs than the standard GUI widgets from the OS nowadays. Custom themes also could lead to ugly visuals in apps and accessibility problems.
Not really. Designers expect prettier designs than standard GUI widgets, I'm not convinced users have ever wanted non-standard widgets. In fact, more than a decade of bitching-about-java has taught me that users hate non-native widgets. But hey, developers love them so fuck users.
Native widgets play significantly better with all accessibility tools, in part because native widgets are so customizable. You didn't need bespoke "Dark Mode" that was some designer's wet dream of what an interface should look like, you could just customize your widgets for what you needed: https://66.media.tumblr.com/19cb7fe3e0eef36debbd0167d6e6e0ea...
Do they though? I've had several family members buy Windows 10 PCs and they specifically requested I 'install Windows XP on it' (install Classic shell + a few other utilities to make the shell look more like Luna or Aero depending on the requestor)
I'd say users expect things to look like what they are used to, whatever that user-specific preference is.
