The grease should be nothing less than perfect. It is difficult to open the greased area without having debris fall onto it. If you can guarantee that no debris would rain on the grease then no repacking is necessary. But no mechanic would advise that. Considering all the road grime and brake dust on the outer surfaces and crevices, repacking a bearing is the recommended practice after opening a bearing.
95 E320 Cabriolet, 131K