Wii uses a proprietary API (similarly designed to GL) called GX, and the PS3 has a proprietary API called GCM, which is much more low level than GL or D3D. The PS3 also has a wrapper called PSGL, but this is different to "Desktop GL" and is a translation layer (like Wine's D3D->GL layer). The 360 has a proprietary API that's quite similar to D3D9.
It is also arguably more flexible, but only in that it is significantly more portable. Writing linux or mac games in D3D instantly makes WINE necessary at a cost to FPS (as WINE must redirect D3D calls to OpenGL), and I'm not sure if the Wii and PS3 support D3D at all.
IMHO, the portability of OpenGL is a bit of a red herring.
On Windows/Linux, the OpenGL runtime is almost entierly implemented by your graphics driver, and there is no governing authority to ensure standards compliance -- it's industry self policing only. This means that vendors can and do violate the standard in ways to hurt each other -- e.g. nVidia drivers accept HLSL syntax in GLSL shaders, with the hopes that developers may ship such shaders, which will appear broken on ATI/Intel GPUs...
On the other hand, Apple keeps a much tighter grip on things (like Microsoft does with D3D), so OpenGL on Apple OS's is going to be a lot more reliable.
So the 3 platforms that GL gives you portability to -- Linux/Windows and Apple -- all actually may behave slightly differently. You still need to test your renderer separately on each platform, and on Windows/Linux, you also need to test your renderer on GPUs from each manufacturer, as each of these tests is against a completely different implementation of the OpenGL runtimes.
Also, if you want to support the latest SM5 GPU features, but also support scaled-down versions of your renderer for SM4 and SM3 GPUs, then you've still got to "port" a lot of your rendering code no matter the API.
On Windows with D3D, you'd have to maintain a D3D11, D3D11_feature_level_10 and a D3D9 version of your renderer.
With GL, you'd have to maintain a GL2, GL3 and GL4 version of your renderer.
So a "cross platform" renderer has to maintain and test code for:
Consoles: GX + GCM + "D3D360" + any other consoles
Mac: GL2 + GL3
Linux: GL2 + GL3 + GL4 multiplied with ATI + nVidia + Intel
Windows plan A: GL2 + GL3 + GL4 multiplied with ATI + nVidia + Intel
Windows plan B: D3D9, D3D11_10, D3D11
Mobile Phone: GLES1 + GLES2 multiplied with each Android + iOS device
Yes, sharing common GL code paths might be able to save you some time, but no matter which APIs you use, it's going to be a hell of a lot of work.