It was an unexpected change from a security project to be enforcing a theme on all the pre-installed apps.

We're not enforcing anything. We replaced the legacy icons with adaptive icons following the same style we've been using for years.

As a user of your project, it would be nice to have respect shown towards me and my everyday experience of the UI, especially as updates are automatic. This change seems unnecessary and a downgrade for my user experience.

You're claiming we aren't respecting you because we updated our icons. This isn't appropriate behavior within our community.

The new icons are a matter of personal taste, and are very minimalistic. Why not leave it to theming apps that are available to provide unified icons?

You're welcome to use a different launcher with icon pack support to replace our icons if you don't like them. The legacy icons had to be replaced one way or another and these are the replacements we made. Most of our users like the changes and we made a new revision of the icons to improve them and make them more consistent.

If the legacy icons are not coming back, please can you consider adding some colours and making the icons look different to each other, in a way that themeing apps cannot provide. Maybe they could be copies of the old icons?

The old icons are not coming back in any form. We didn't make those and they were ugly low resolution bitmaps with no coherent approach.