"Command" mode?

I came up with this idea while I was thinking about how someone could catch up with Vi while keeping the usability of a traditional editor. Eventually, I realized that the problem with Vi is that the insert mode should be the default mode.

Essentially, Kate would behave like normal until you typed a hard-to-do-by-accident key combination that would activate “Command” mode. From then on, every combination you used would be treated as though the Ctrl key was being pressed.

This might be redundant due to Kate’s vi mode. Thoughts?