We have a bunch of Core Basic deployed and took the guts out of the included Battery Bottoms and put tape on the gaps. Since they're always powered, we had a few batteries start to bloat and also occasionally something would short the pins, so gutting them was the easiest solution.

Not everyone needs batteries or extra expansion, and an extra plastic piece wouldn't cost much. I just though it would be nice to have just a simple piece of plastic cover... potentially with screw slots to aid in mounting