I don't believe it's 'soft, fluffy idealism' but the rule of law -isn't that part of what we're fighting for & what hopefully differentiates us from the terrorists?
Across the pond unarmed black men are being shot by the police whilst on the ground with their hands up, because officers are so nervous. Arming all service personnel at all times, even were there enough weapons to go round would inevitably lead to accidental deaths of innocent people. Even highly trained armed response units get it wrong sometimes (eg: the Brazilian electrician on the tube), the last thing we need right now is some tommy/erk or matelot blazing away at someone because that someone happened to be non-Caucasian & 'looked at me suspiciously'.