The majority of Linux distributions out there seem to be over-engineering their method of distribution. They are not giving us a new distribution of Linux. They are giving us an existing distribution of Linux, but with a different distribution of non-system software (like a different desktop environment or configuration of it)
In many cases, turning an installation of the base distribution used to the one they’re shipping is a matter of installing certain packages and setting some configurations. Why should the user be required to reinstall their whole OS for this?
It would be way more practical if those distributions are available as packages, preferably managed by the package manager itself. This is much easier for both the user and the developer.
Some developers may find it less satisfying to do this, and I don’t mean to force my opinion on anyone, but only suggesting that there’s an easier way to do this. Distributions should be changing things that aren’t easily doable without a system reinstall.
base arch only installs the “system software” as you call them. all the “non-essentials” are indeed just packages like you seem to want them to be.
I am pretty sure arch installs a decent amount of non-system software, but I suppose that’s beyond the point.
What I am suggesting: if you make a new distribution, whose only change from its base distribution is changing non-system software, then I personally think it should be available as a package. This doesn’t mean I am saying Ubuntu or Fedora should remove non system software, and follow arch-like model. Absolutely not. These distros change things that aren’t easily packageable.