I've heard that about centres as well, though it wasn't like that when I was in them many moons ago. I think it's more of a safety issue...not having crawlers in a room with a bunch of exuberant walkers/runners - risk getting stepped on, etc. Also, they want kids to be as autonomous as possible, even as toddlers. I wouldn't keep them on in your shoes. If they wish to move to daycare centre, that's their call, but you have your own business to think about. They want big daycare centre, they get all the not so awesome parts of it too