I’m not as bothered by it as some people on here, but my general opinion is socked is fine. Certainly preferred over shoes or bare. Always shoes in the toilet. I tend to wear my laceless Converse slip ons when I’m flying so it’s easy enough to take on / off. Not a fan of feet on the bulkhead (socked or otherwise) but not bothered enough to tell someone to stop doing it. Feet on tray tables (socked or otherwise) is unnecessary but I’ve never encountered it personally.