Crank case ETZ and possibly other models...

[Sisyphus]

This is more a question out of curiousity rather than help.

So my crank case has been of the bike while repairs are carried out, and I noticed that inside the crank case it has a patina (possibly the wrong word, but raised half spheres) alll along one side... why is this? Do they serve a purpose, the way transmission oil interacts with the clutch? But why do the cover the whole side, surely half would have been enough and less effort? Are they for cosmetic purposes, then why are they on the inside.

Could somebody shed light on this mystery for me please?