"In the US system, you put your deicing gear on if it is snowing because FAR number x subsection y clause z says put the deicing gear on."
Hmm..yeah, and what about Company Ops Specs and a bit of commonsense? If you see ice build up (1/4"+) and you are flying into unforcast weather (do I hear "Flightwatch"?), I think I'd like to activate the boots and pitot heat.