I disagree that side clip are merely aesthetic and add nothing to the strength of the action.
I agree they do look good, but I also like actions without them and only have one gun with them.
I do agree that they add technical difficulty to rebarrelling.
I find they are more common on German Guns and while I do believe that German guns often seem over strengthened I have some faith that when the Germans do something technical it tends to be correct, though maybe overkill. My experience with German engineering (cars, guns, optics, etc.) is that it is more often than not, correct.
While they are redundant to other locking points and may not be truly necessary I believe they do add something to the strength of an action.
