I had two sets of panels and made a play yard twice as big for my twins when they were babies. the play yard panels were brightly colored had a gate and toys build in.They took over the whole room but were happy for hours on end. It was so big we could go in there too. We also gated off the porch and put special netting in between the porch rails. This made the whole porch safe. All their big toys, ride on, activity table, would be in there also.
I agree they are no different than a crib or the pack n play/play pens. just bigger. as long as they are not used all day long they can be a big help to the mom who needs to keep them safe while she runs to change over a load of wash or run to the bathroom.