Originally Posted by
Yachi
I agree to OP's suggestion, with a slight tweak. Auto re-arm traps only when you are not given a shield (ie failed attack, or you could say, a successful defence). Before the sneak peeks, I had initially suggested auto re-arm at no cost for a successful defence. That is our "incentive". However, I'm satisfied with lowered re-arm costs.
Do understand that after the update, it will be more difficult to obtain a shield, especially at higher TH levels. Imagine wave after wave of unsuccessful attacks triggering your traps. Eventually, your base will succumb to the final wave because all prior attacks have paved the way, making it easier. Same principle to auto re-arm traps for clan wars.