I have bent them inward slightly then eased them onto the port tops. The end result is a small tab placing a minute amount of pressure on the top of the ports. I just assumed that was what they were for. They don't look like production tabs (like plastic models), so I doubt they are left ver from the moulding process.
Just guessing.
I just noticed the smaller tabs and remembered that I left them on, and I do not have any issues with plugging peripherals in. Again, slight pressure against the face of the port.