^ My understanding is that they are pinned before they are welded, so the pin or whatever it is comes loose and makes an annoying noise. It doesn't affect the durability since it's just there to hold it in place for the welding, but it's annoying when it comes lose and rattles around. I don't have Open Pros, but one of my Reflex rims does it and two of my family's Open 4 CD rims did it. It seems to be a Mavic Trademark.
You're probably right that overtensioned spokes probably causes cracked eyelets, but that's probably the case in most any rim by any brand. To this day, I swear that Sun has the smoothest seems of all the brands I have tried. Even Mavic welded seems are a little bumpy if you look closely.