It doesn't attain C-level speed yet. Maybe for a web developer's purposes it does, but definitely not for the kind of ridiculous optimizations that console games frequently need.

Further, C/C++ runs the industry, and that's all the console manufacturers are going to provide for in their SDKs beyond scripting, such as Lua. Even then, use of that has to be limited because they're usually so cramped by the hardware.

http://www.wiisworld.com/wii-specs.html

88mb of memory in the Wii.

Lets not forget that you have to interface with OpenGL / DirectX for the graphics. Good luck wrangling with OCaml for something like that.

Oh, and you'll have to retrain everyone anew for it too.

It's just not a good enough tool/language to justify the switch given the immense inertia weighing against it.

Edit: This is why I don't work in the gaming industry, amongst other things.