These movement keys are at least 40% the reason I love and use vim or vim plugins. Not having to move my hand, and being able to “drive” with only one hand are immensely beneficial.
With cursor keys, it feels like half of my editing time is spent finding the arrow keys and then finding the home typing position.
Emacs ctrl n/p/f/b are better than cursor keys often, but they require two hands.
The best part of evil-mode in Emacs is that I get to use Emacs bindings in insert mode, and then vim keys in normal mode. For instance when writing function signatures, I can hit C-f to easily jump over the closing parenthesis, or C-e to easily jump to the end of line, usually also to skip the closing parenthesis. I'm not sure how you would do that in vim without exiting back into normal mode and using for instance S-a to append at the end of the line.
From insert mode, vim lets you run one command without explicitly switching back to normal mode. :he i_ctrl-o for details. It's very handy for positioning the cursor for more input, for example ctrl-o f)
Also works in evil.