I agree, there are several competing CAM formats, as well as the fallback option of "plain old gerber". Ucamco, as the new owners of "Gerber", have been aggressively pushing their own proprietary format, encouraging CAD vendors and users towards X2. Obviously, with the plan that PCB manufacturers then buy X2 compatible CAM software from Ucamco.
I really don't know why KiCad got into bed with Ucamco, JP Charras seems to have a working relationship with them, I don't know if Ucamco provided any sponsorship. I would have preferred a generic solution in KiCad, and plugin modules to support specific vendor formats. Getting locked in to X2 doesn't seem the right direction to me.
It's a win for Ucamco anyway, they quote KiCad in their marketing material.