For whom is it useful to write his custom image? Maintenance? Added value?
It’s not good to layer too many packages on top of the normal atomic Fedora.
If you still need a special configuration, like for Nvidia (“silverblue-main-nvidia”), gaming setup (“bazzite”), non-supported DEs/ TWMs (e.g. “deepin-main”) or special hardware (e.g. the Asus ROG or MS Surface), you can just download it and have everything in one go and working as a whole.
This is not only very convenient, but also more reliable, since your baked-in Nvidia driver for example/ config is the same as the one from thousands of other users, including the developers.
It prevents the “But it works on my PC”-problem and helps troubleshoot issues way faster and more precise.
Anecdotally, KDE has been a mess for me everytime after a few weeks for example.
This is due to package drift.
On my Kinoite install, it is actually usable and doesn’t have nearly as many bugs as on the normal Fedora KDE variant. Just, because the install is the same.
When is it useful to deviate from fedora and use a ublue version? You don’t have a fedora signed distro anymore. You have to trust another party blindly not to inject malicious code. Risk of not being maintained anymore.
Pretty much always imo.
Fedora isn’t allowed to ship some stuff ootb, and uBlue tweaks it for you.
Also, you get more choice, as mentioned above.
uBlue isn’t much derivated from the OG Fedora Atomic, and it has a large user base.
It doesn’t need much maintenance, since it is mostly automated. That’s the main pro point compared to forked distros like Nobara. Also, it’s signed.