I'm guessing they went for the long-pressing because it's an incredibly easy action to take. The hit region is massive, so you just place your thumb on the screen and hold.
Having to draw a checkbox with your finger requires you to hold the phone and then flick a checkmark shape with your thumb (a difficult task), or else use your other hand to draw. If you're right-handed, you're probably holding the phone in your right hand to begin with, so now you have to switch hands to hold it in your left and draw with your dominant, right hand.
Having to draw a checkbox with your finger requires you to hold the phone and then flick a checkmark shape with your thumb (a difficult task), or else use your other hand to draw. If you're right-handed, you're probably holding the phone in your right hand to begin with, so now you have to switch hands to hold it in your left and draw with your dominant, right hand.