Wow you first got 1.5TB for about 600, and I get 7TB for $600
+1 to you my friend.
I stream to 2 ATV in my house,( it's called a network) I use my computer too, for more than Itunes too 🙄 It has my whole DVD/Music collection too🙄 Good luck downloading 8.5TB from the cloud 🙄
Lets See here
Large HD and Externals
HD Fails (has duplicate HD offline)
Case Fails, (Take HD out and Put in New Case, Any case will do)
Simple
Server or NAS/RAID
1 HD fails (Raid/Server OK)
2 or more ( Cry and hope you had it backed up)
NAS/Raid Fail ( need to replace with same controller or case,)
Server parts Die🙁many parts can fail)
OS issues
Motherboard Died
Raid/HD Controller
PSU
Needs to run 24/7 in most cases
Complicated
Time and $$$$$$$$$
nothing more Gained
Based on your comments it looks like you really don't understand unRAID, its advantages/disadvantages, features, etc. I spent about $200 on my system (minus the drives). It is capable of handling eight drives with out adding any controller cards. I only have 2 2TB drives and 2 1TB drives currently, but I will probably be adding drives as my Blu-ray collection is growing fast. This type of system isn't for everyone, but it has so many advantages over the method you are using. It is just a matter of whether those advantages are important and/or necessary for what you are doing with your data.
Your storage method isn't dumb by any means, but your attitude toward what other people are doing with there data is very dumb. Just about every one of the negatives you listed against "Server or NAS/RAID" shows a misunderstanding of the system.
It isn't that hard to set up (I knew very little programming or Linux commands when I did it).
If two or more hard drives fail then you lose part of the data on those two drives (what happens if your drive and its backup fails?).
If any part dies, you replace the part and the system is back to normal without any changes to the OS (which runs off of a flash drive; I have a backup of my flash drive as well).
The file system is not linked to any controller or RAID card, so you don't have to go finding a replacement exactly like what you had.
It isn't that complicated. Surprisingly, it is very simple and reliable after you set it up (which is no more difficult that building your own PC).
You could argue that it saves time from continually hooking up drives for archival purposes. The redundancy is done automatically. I have already had drive failures, and it was a very easy recovery.
You gain quite a bit over a simple external drive system. Your data is not tied to any specific computer. I have found that sharing your data to both Windows and Mac systems with unRAID is so much simpler than using external drives connected to one system. And are you saying it is simpler to keep up with all archiving of drives rather than just letting a system do it for you?
I'm glad you found a system that works for your needs, but that doesn't mean what works for you is even close to the best system for everyone else. I set up a Mac Mini home theater system with Plex for a friend of a friend so he could house his large DVD collection on some type of storage system and use Plex as the interface. I decided not to go the unRAID for him because he needs something very simple, so I set up a DROBO for him. It met his needs well. Either of those systems is superior to external drives. Otherwise, people wouldn't pay for them. But it comes down to what someone needs.