Do you wonder why it is just PJs? Why not all clothing children wear. I made nightgowns for all my girls back in the 50's, 60', 70's. They are all alive today. First of all my children got in their nightclothes and went to bed. Didn't play in them. Second I watched my children. This whole thing started back in the 70's when 2 children died because they were playing in front of an open fireplace. No screen. Parents were upstairs otherwise engaged.
You are right about the prints on flannel, most are for babies or children. Go figure. A lot of our fabric is made in China. Do you trust their processes?????