I was among the first ones who tried unofficial method of moving overlays from system/overlay to data/overlay on my S6. I also tried installing those overlays on my non-rooted Note 5 and to some extent they did work.
However when sungstratum first published in Play Store, even rooted people had to buy the addon which I happily did. It was quite surprising to see something like substratum on Samsung's closed source touchwiz specially considering the quality of themes in Samsung's own Theme Store.
However I disagree with this
I don't know when you changed play store description but back then you guys clearly stated that this will work later on.
An add-on to enable rootless mode for Samsung devices (Nougat+/7.0+) on our main theme engine Substratum downloadable here: https://play.google.com/store/apps/d...ekt.substratum
And now Samsung users have to pay twice to use substratum rootless which obviously they don't appreciate.
On the other hand, working on these kind of things and getting to stable stage is pretty time consuming, hard & sometimes demotivating. We saw the first lines about themes in Lollipop source code, and Google is still delaying the announcement of Theme Support in AOSP after three years. And [projekt.] team are the only ones who work on this ahead of time as far as I know so they need real support.
If you find rooting your device complicated and difficult (Which for the most people is the main reason of not rooting),before ranting devs take a minute to think how difficult and time taking substratum can get.