> The existence of "modes" is also opposite to the approach which is know for decades to be less prone to accidental errors: having no modes and always being able to perform more undo steps.

vim has had the multi-level undo and redo for a number of years. If I really screw up, I can always run something like :earlier 5m to get back to the state I was at 5 minutes ago.

The only problem I have with some of the normal mode keystrokes is when I want to use some of the window based shortcuts and accidently press ctrl-w while my browser window is open (which closes the tab) :)