I understand why they have floor outlets but I have never been comfortable with them. You sure have to plan on them getting wet if you mop or even spill something. Those brass plates may be expensive and they will keep the big chunks of dirt out but they are certainly not waterproof. I think of the brass as a grounding device, similar in function to what you have in 680.26. There may be a puddle in and over the plate but hopefully it will be at ground potential until the O/C device opens.
In one of our projects (Rookery Bay Nature center) I "suggested" and got GFCI protection on the floor outlets, based on the risk of flood. Fortunately the customer/builder was concerned too and was looking for guidance.
