The title says it all.

X-Box 360 got most of the add on content and not the PS3.

For instance. The only dlc's available on PS3 are Knights of the Nine and Shivering Isles and that is all.

X-Box 360 and the PC recieved like 8 plug in's. Horse Armor, the Warlord's Castle, Vile Lair, etc.

None of which was available on PSN nor on another version.

I'm wondering why Bethesda neglected to do this.

This is pure speculation on my part, but I'm going to assume it's due to the same reason there were problems with Skyrim's DLC.

wait. horse armour was real?

As a ps3 player i thought that horse armour was some weird april fools prank.

I really doubt that neglect had anything to do with it. After all, you're talking about profits. I bet there was some kind of legal or contract issue.

Oblivion was only on the PC & Xbox when it released.
It came to the PS3 a year later.

I speculate a deal with Microsoft might have also kept the add-ons as an exclusive for their console.

There we go I fixed it for you.

Yeah, thats what I'm thinking. Still svcks that TES fans on the PS3 had to miss out on those.