The pre-Orsinium blackwater blade campaign is what made me fall in love with PVP. So many great memories. I don't want this campaign simply for selfish reasons though. A few of the benefits it provided were:

• Hybrid builds were super viable
• Everyones base stats were the same
• Damage and healing was not out of control
• You could safely go in there with lvl 10 armor and make it all the way to 50 without re-crafting
• The fights were far more interesting because of the different build varieties
• Crafted armor was pretty awesome. Quite a few actually ran sets like Willows Path. Hell, I remember running Ashen Grip =D
• Server performance was so good
• It was truly a great place for newer players to experience PVP for the first time.

The last point is probably the most important. Even a complete nooblet would not get insta killed, because gear was not such a huge factor. A set of green armor would have the same stats as purple ones. Let's be honest, not all newer players are able to afford re-crafting and improving their gear every 4 levels like veteran players in non-vet do.
PVP back then was a lot more friendlier than it is today. Still competitive, but much less hostility and bickering. Probably because many of the points I listed above.
I truly believe a pre-Orsinium campaign would be good for ESO, and I really like watermelon.

Please consider it ZOS.

Much love.