And what advantage does it have over RAID "zero-configuration" enclosures? Probably not any cheaper, will be less flexible (cannot upgrade or replace the disks), and less secure (if the shared electronics fail). I think "Please buy 2 identical SATA harddrives of your desired capacity and put them in the slots" (at least they can just show the box to a computer store sales, who will show them their options) is user-friendly enough? Or are you saying people are too lazy to even do that, and will be willing to accept the aforementioned disadvantages in a tradeoff?
Do you think media replaceability would be important? HDD capacities double every year or so, right? (Just a guess, I don't have the numbers.) I think most home users wouldn't mind getting a completely new, larger drive at the occasion and be happy that they got a "The system drive is failing. Please backup all data and replace the drive."-message instead of total data loss