I didn't see the problem with arrow keys either. They really do break flow though. I only recently discovered how much better the home key navigation is over arrow keys. Every time you move you hands away from the home row you incur a small mental task of making sure that you move your hand over there and that the hand is correctly positioned. It sounds trivial but it really adds up to one less thing to think about.

Couple this with inoremap jj <Esc> and it eliminates the majority of large movements away from the home row.

Say you are in the middle of a word that you want to change compare: Arrow key right until at end of word, i, backspace until at start of word, type new word, Esc three excursions from home row.

Ciw, type new word, jj. No excursions from home row and less of a mental load.