but what purpose will there be fr the xbox one if already has an api with low level access?
as for crossplatform development with ps4, i thought that both nintendo consoles and sony´s ones used a derivate of the opengl api, so dont see how directx12 adaptation could be an issue for microsofts console

as far as we already know, consoles have always offered low level access API to give better performance than the PC games, so how much improvement coul directx12 offer to xbox one if this console has been using another api with low level access since launch?. I am sure there should be some improvement but dont see it as vastl good as the improvement for PCs

It's over. PS4 is finished. DX12 trump card will put XB1 leagues above the competition.

Because it's more evolutary (or revolutary) than just low level access.  It changes how the CPUs talk to the GPUs.  So much more utilization of the  GPU can be achived.  There is signifanctly better opmization - at least on paper.  It's also could explain why the Xbox One has a much larger cooling system than it seems like it needs.

And it will help standarize develoment across PC, Xbox, Phone and Tablet because of scalibility.

Plus, there are already some new tool out that helps developers optimize their games, and more coming that have not been annouced yet.

Think of it like a new operating system for the Xbox One.