JOSM seems to display the contents of note=* in the relation list; at the moment 55 900 relations have a note=*, whereas 13 500 carry a description=*. This usage of note=* is a bit different from note=* used on ways and nodes. I'm inclined to believe mappers have used it on relations because it makes editing easier, when description=* would be more in line with the other uses of these tags outside of relations. It would be best if JOSM were to use the description=* before a note=*.