Probably to remove the negative taste of Activision spending 6 billion for a phone company.

http://www.escapistmagazine.com/forums/read/7.884377-Modding-And-Mapping-Tools-Coming-to-Black-Ops-3-PC

Anyway, your move EA/DICE, "Battlefield 3 cannot have modding tools because Frostbite 2 is just too complicated for modders to tackle"

Just in time for paid mods to get working on Steam etc.? i wonder if there is some clause that all the created user-content is automatically the property of Activision?

Perhaps.

Or I guess Call of Duty Elite so far has been a failure.

Modding functionality was added thanks to the King buyout. You'll be able to play mods, but you will only have a limited number of lives in the mods, which could be increased by friends on the app or Facebook accepting your help requests, or if you pay a small sum.