On weekday mornings I get up and see Mr Acorn off, then go and get abluted and dressed (a luxury of working from home), so that's one opportunity to wear a nice robe. Quite often in the evening I get changed into something comfy but nice - an opportunity for a posh-pyjama-type outfit.
My Mum, in the '70s or '80s, had a dress that she often wore in the evenings - long, brightly coloured velour - and I think that's where I got the liking for having evening-at-home clothes.