I wonder if it is to do with the fact that many years ago our mums didn't have 1800spin washing machines and tumble dryers and did have loads of terry nappies etc to wash. Perhaps with the mountains of washing and not so much room to dry them, they were put into the airing cupboard to dry them out completely. My granny used to iron everything or 'smoothing' as she called it, you name it, fuffly towels, socks, pants, everything. I would also think that in that era it was easier to 'smooth' things when they were slightly damp, hence put them in the aring cupboard afterwards. Personally, I iron very little, mrwarpigs work shirts and trousers, duvet covers (but only the nice ones), everything else is done as and when I feel like it, if ever!