"Let it melt" is fine if the only cost is the odd down-day. How far do you let that argument run, though? What about a down-week? Or a down-fortnight? What if that down-fortnight is at a crucial period of work-up training for a deploying unit? Perhaps that unit could send a detachment to an airfield with better weather or better clearing equipment - but being away from home just before a deployment would obviously not be popular!
Whilst on this subject, could someone with knowledge of "Clearway" please explain how major airports are able to use it to maintain operations in all but the heaviest snowfalls, whilst most RAF airfields seem to use it to create a surface worthy of Torvill and Dean!