I would say that's fine for Easy to drop their ISO9660 distribution format. The rationale makes good sense.

And of course I'm going to fit in the mold of an entrenched, elderly, "old timer", digging in his heels and I'll re-state a fossilized opinion:

In general, the ISO9660 format is great for distributing disk images for this reason: it's a mature, international, cross-platform standard.

This is not important for a Linux distro that can be set up with ext3/4. But if you distribute something with wide compatibility, you'll still consider making it ISO9660, because a Mac user can roll with it,* and a Linux user will have no problem, nor will a Windows user run into difficulty mounting and reading it.

Likewise, if you wish to generate this filesystem image, any of the above systems, and more, will have an app to create a standards-compliant ISO9660 image. In fact, most of the apps will help with staging all your data and assembling it into a nice package, that you'd otherwise want to make something like a build script to go from a bundle of files and data to a finished ext4 image.

But for Easy, and any other Linux distro, we've long ago phased out actual optical discs (my elderly fossilized brain recalls Knoppix as a revolutionary "live CD only" distro) so swapping in ext4 images may liberate some devs and support techs.

*I don't know actually--do Macs have built-in tools for ISO mounting? They had their own sort of ".dmg" file for "mount as a disk, install this software package", last I checked. And one popular extension is ".img", so Linux distros--stop confusing Mac users!