Sometimes I also share the same thoughts as you. I know that Unraid is, in a way, a form of software RAID. However, I don't use this feature and use it in the way SimonF uses it. The only difference is that I use hardware RAID. (Of course, both hardware and software RAID have their pros and cons.) Using HPE Smart Storage, I have created raid 5 logical storage drive. Unraid detected my hard drive as one 8TB logical drive. I have zero problems with installing vm, docker, apps, plugins vs so on.
Actually, asking Unraid to remove this feature is completely contrary to the original purpose of Unraid. (A bit funny, but if you remove the RAID part, it will be left with just "UN" in its name 😂) Because all the other features of Unraid (VM, Docker, etc.) are essentially open-source software that can be installed on a plain Linux. But there is a difference, and that is Unraid has beautifully and user-friendly shaped all these features. They have done this in a really successful and commendable way. What I mean is, even if the RAID part of Unraid is removed, I'm sure many people will want to buy it for the convenience it offers.
Releasing such a version of Unraid would provide advantages to users.
1) Since this version is essentially composed of many open-source software, it can be sold at a more reasonable price. I'm sure many people would pay for a product that brings together all these features so successfully.
2) You won't need to stop the array to make some changes in Unraid settings. Because currently, you need to stop all VMs and Dockers every time you want to make some changes.
3) As you mentioned, some concepts will be simplified. No such as pools, parity, cache, aray, mover.
4) Maybe a performance increase? I'm not very sure about this, but Unraid is, after all, a kind of software RAID. I'm sure the RAID software is running in the background. Even if we don't use this feature, could removing it result in a performance increase? I wonder about that.