I just realized that I forgot THREE edited extremely important points:
1) you can lock JABBA barrels to one item, which saves a lot of trouble with precise piping systems. Even if you aren't using pipes, seeing you have 0 of something feels a lot more organized than having empty holes in your barrel wall.
2) dollies. How could anyone live without them? No, portal/gravi guns are not an alternative, I don't like accidentally shooting my chests miles away or replacing blocks with them.
3) you can double-right click them while holding any item, and they will store any of the same item in them no matter what's in your inventory. That's amazing.
Factorization- because you can only pull from the top/bottom. Having a few rules like that leads to more creative designs.
More content/function does not equal a better game.
I don't see how being forced to be creative is a good thing, I'd rather have freedom in what I can do. Plus, 1.6 FZ barrels can be rotated and accept inputs from behind, so it's not like you need that much "creativity".
I wonder why no one here even mentions the Barrel Mod...
It's basically FZ barrels as a standalone mod with this strange rendering for blocks, so I don't think there's much to talk about it.
By the way, why would you dislike upgradeable barrels? That 1024 stacks upgrade for old Factorization barrels was amazingly useful, but sadly it didn't survive the major barrel nerf of 1.6.