Arrow keys work fine in VIM, whether you're in insert mode or not. The argument for not using them is that it's less productive to use them than HJKL, because you need to move your hand back and forth between the home row and the arrow keys.
I never broke the habit myself, and I suspect the benefit is a lot smaller on a laptop keyboard versus an AT keyboard.
I never broke the habit myself, and I suspect the benefit is a lot smaller on a laptop keyboard versus an AT keyboard.