Exactly right: bar end weights are used to minimize vibrations in the hand grips -- more to avoid nerve damage (when your hands start to tingle, it is time to take a break!), but being able to see in the mirrors, is an added bonus. My '93 Voyager touring bike had them, OEM. I replaced the grips with foamies, and left them off -- 7,000+ miles later, and no issues with nerve damage, or mirror vibrations (mirrors are mounted to the fairing, not the handlebars, though...
).
Since this topic has come up, I would highly recommend foam grips: inexpensive, reduce vibration to virtually nothing in your hands, veeeerrry comfortable, particularly on long rides. To remove the old, cut them off with a razor knife; to install the new, you can use grip glue, or wrap the bar ends with masking tape, and slide the new over it -- add enough layers to make them stick securely, but still be removable, if necessary; another option, is to use RTV Silicone -- when it's time to remove them, just grab, and twist, to break the RTV loose. Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII