I guess the usefulness of voice (I mean in terms of intuitive interface, not immersion), is mostly where there's a huge number of unstructured choices. I agree MMOs and RPGs could get interesting, because they always struggled to make a good interface for spells and abilities. Since 1999 all MMOs are still using the Everquest-style array of icons mapped to nearly half the keyboard. I don't know if voice is the solution, but someone has to find a way to improve that interface.
There's also games like R&C which have dozens of weapons and tools, it's a mess to map them all on the quick-select wheel, and multiple pages. it would be more intuitive to call the weapon by name, because I'm often too busy not dying. In single player they wouldn't have to pause the game anymore while doing the weapon select, and it would be more consistent in coop and multiplayer (because the game can't pause in these modes).
There's also games like R&C which have dozens of weapons and tools, it's a mess to map them all on the quick-select wheel, and multiple pages. it would be more intuitive to call the weapon by name, because I'm often too busy not dying. In single player they wouldn't have to pause the game anymore while doing the weapon select, and it would be more consistent in coop and multiplayer (because the game can't pause in these modes).