Hey there Art Ink Studios! Thank you for reaching us.
The solution you proposed is indeed more Arcade-wise, but in our case that can't be implemented due to the fact that you need a hand on the mouse too, to aim. For this reason we preferred choosing controls on the left side of the keyboard.
We will think about considering a different input set-up involving Arrow Keys in the future, so don't forget to check once in a while!
Thank you for your feedback and for playing our game!