John, the mods to the guitar you pictured are simply those of a previous owner. We can speculate as to why he chose to drill those holes and add those screws, but we'll never know for sure unless he speaks up...which is doubtful. (People who do foolish things often don't like to admit to doing them.)
Some years ago, I bought a Fender 400 which had similar issues. Though it was in decent shape, the underside of the guitar had
37 empty screw holes in it, where a person, or "persons unknown", had probably added knee levers, an ash tray, a wine cooler, a tool box, supercharger, and various other "accessories", only to later remove them.

It's an unfortunate fact of life that the pedal steel guitar, due to its mechanical nature, invites tinkering, modifying, and tweaking, and many times these efforts are made by those with good intentions, but poor understanding of mechanics and aesthetics.
