I've sailed a Topper without shoes a few times, and honestly, it really helps with balance and grip because you can feel the deck better. But going barefoot means you're not protecting your feet, there can be sharp areas or hot spots, which can be quite risky, especially for kids.
That's where barefoot-style sailing shoes come in. They provide solid traction while keeping your feet protected, making them a great option if safety is a priority. If the deck is clean and smooth, going barefoot can be fine, but for kids, I'd definitely recommend barefoot shoes just to be on the safe side.