I think you have a good point that most people prefer to use the mouse, and commands that may seem obvious for some people may not be immediate for another. A clickety pointy UI would make it's affordances more immediate for the user, and I bet that they will look into that in the future. (In the lastest version, you can call ubiquity actions with a right click on the text. That's a start)
Given that, I do find ubiquity much more user-friendly and useful than commands in the terminal, for the tasks it was designed to use. For example, you can select a whole page, just alt-space, write 'translate to chinese' and it substitutes the text in place, fast. In your email, you can select an address, write 'map' and insert it in the email almost instantly. You can save many seconds and mindshare with this tool.
Given that, I do find ubiquity much more user-friendly and useful than commands in the terminal, for the tasks it was designed to use. For example, you can select a whole page, just alt-space, write 'translate to chinese' and it substitutes the text in place, fast. In your email, you can select an address, write 'map' and insert it in the email almost instantly. You can save many seconds and mindshare with this tool.