Well currently my perceptions on OMV installations on SBCs (specifically RPi4) is that they are treated like "seconds class citizens" in OMV forum.
Pre-RPi4 that is true. Rpi4 is a good board. I have three. And why would a second class citizen have very specific code in the install script?
"Years of practices and past recommendation" have, from my view, been invalidated by technical improvements delivered via the RPi4 and similar SBCs
Bullshit. I own and test most of the popular SBC boards. So, this is just nonsense. You may be referring to old threads but I am quite sure my current advice when people ask is as current as possible.
It's time for a change in attitude towards this group of users and revised recommendations.
Says who? You? I almost never see RPi users asking for recommended hardware. They buy what they can afford. It is almost always higher spec amd64 systems.
An example to illustrate the topic, is to change recommendations from "no (software) RAID" to "only use hardware RAID using verified HDD enclosures".
Why? Once again, you don't see to understand the budgets of a large number of sbc users. Your icy box enclosures may be nice (i have a few of their multi 2.5" to 5.25" enclosures) but most do not want to spend that much. And if they are using raid and can only afford two drives, where is their backup??? If they use borgbackup, not only do they have multiple backups with bitrot detection but they still have redundancy (you can mount borgbackup archives directly in the plugin). Your raid suggestion gives no bitrot detection or protection against crypto viruses or accidental deletion. Good thing their empty or encrypted drive is still working when one fails.
To support this technically the software RAID configuration application (mdadm) should be de-installed during OMV installation and the reasoning be explained in the "new user guide".
You will have a lot of fun supporting the destruction you cause by telling people to do that. mdadm is a dependency of OMV and you will uninstall OMV if you uninstall mdadm. mdadm is not a plugin.
Prediction is that "80% of use cases covered by OMV are well served by an SBC with external HDD enclosure connected via USB3"
Thank you captain obvious. Over 80% of SBCs don't have sata ports and have to use hdd enclosures. I said don't use usb raid NOT usb hard drives.
Does this start to make sense?
Only in your head. Unlike you, my recommendations are formed by interacting with users to see what they need NOT what you think they need. Since you preach continuous improvement, you should know that one important factor is customer satisfaction. Can you show me someone unhappy with my recommendations? Or even someone who would have avoided a serious issue if they were using your recommendations?