I understand why they wouldn’t want to suddenly change the branding of existing projects though.
I’m not sure if I agree, I feel like the long term damage of keeping the names is greater than changing them now to Fedora Plasma Atomic (Formerly Kinoite) / Fedora Atomic Workstation (Formerly Silverblue). Leaving them as is, is just going to create more confusion in the future to new users who won’t immediately understand why the naming convention is different for the other spins and will create more confusion for documentation / support threads online.
Whatever file format I use them in is also how I back them up, I backup my entire desktop’s and laptop’s data to an external hard drive and an online service provider. I’m sure a compressed format would be more space efficient but that would take much more time given my use case.
In the case of my laptop it runs Linux and the filesystem I use supports “transparent compression” (almost all contents of the drive are compressed with zstd), so I’m guessing any of the ROMs on there will have already been compressed as nuch as they can (but I’m not knowledgeable enough on the file format specs)