When we first toured NZ, we were SO impressed by the heated towel racks in all the hotels (which were only 3-star). "Wow," we thought, "isn't it lovely that they're so into this little LUXURY in New Zealand?"
We very quickly realised that they are not a luxury here: they are an absolute necessity. Unless you wash your towels every 2 days, if you don't hang them on a warmer, they will still be damp and clammy the next time you need to use them – and as others have said, you'll soon find that you're culturing your very own little colony of mildew.