Pardon, which console platform uses Intel onboard graphics?
Or maybe I misunderstood.
None of them do.
However when I add support for an API (such as Direct3D) I do so on all platforms that it is applicable to, for maximum benefit to users (even if it has no monetary value to me), this means Windows will have the choice of using Direct3D renderers at the same time as I add Microsoft Xbox 360 support.
Many features I add for completeness, consistency, and benefit to users (some having video cards whose vendors don't take OpenGL as seriously as they should).
Similarly most of the OpenGL code is utilized on Sony Playstation 3 at this time as well (there is a lower level API that I may switch to at some point if the performance would benefit significantly, but otherwise I prefer to maintain support for this platform using the same primary rendering code if possible).
I think you do very well with that way. The more systems an engine fully supports the more users it can reach. 360 is certainly an attractive market same as PS3. Adding D3D does not hurt too, maybe you find a use for ATI's tessellation too which the 360 provides (should be an OpenGL extension too) - for some cooler player models or so.