I demote, but I also cull and I try not to allow too much creeping demotion. I've struggled with this a lot in the past, but I'm more ruthless now and my balance seems to work well for me.
I demote items that are very luxurious or high quality and still make me feel good and look okay. For example, I have a few very nice cashmere cardigans and silk and cashmere blends that I've demoted to lounge wear and robe duty. They look nice, but may be colors that I'm not wearing as much for a season or shapes that I feel are getting less current. Demoting lets me get more wear and enjoyment out of them.
I cull everything else. I don't allow demoted items to be any significant proportion of my casual wardrobe. I buy specifically for my casual wardrobe. If I let too much demotion occur, it clutters my closet with items that are worn out or make me feel bleh and keeps me from seeing and wearing the things that do make me feel happy. If I keep it in my closet, I feel an obligation to wear it. If I don't love it, that means that I'm wearing it instead of getting lots of good wear for items that I do love and feel happy in. So why am I doing that? It's like being on a diet and eating leftovers that you don't want and don't like while the thing you really want to eat and that is better for you slowly goes bad. What's the logic behind that?