I think mods should be possible on console once the game is fully developed and is stable, if Bethesda could do it don't see why pimps cannot do it. even simple mods that just re-use assets that are currently installed or create something like alternative Creation Club or released paid mod bundles as DLC I wouldn't mind spending a few $$ to get a better game experience...
Quick answer : Bethesda has more employees than pimps.
Each mod needs monitoring/approval by devs before released, it means a dev busy just for that.
Long answer : I will use examples to make it clear. No adv intended.
There are currently two types of games allowing mods :
- Farming Simulator 2017 (and Creation Club) : Mods are submitted to the devs, tested by the devs, and legal issues/copyright infringments/QA is up to the devs and publisher.
There are considered more or less as free (or paid as of Creation Club) DLCs.
- Skyrim/Fallout : Mods are submitted to the devs/publisher, NOT tested and NOT QA by the devs, and those with legal issues/copyright infringments+additional scripts(Sony consoles only) are refused or removed.
There are more in the PC mods spirit.
Yes, The Fun Pimps/Iron Galaxy can release mods as DLC packs, the easiest way, but it means more devs working to check those mods.
More DLC to sell means more income, developping and testing DLCs means more expenses.
The decision is up to the dev team.