If everyone agrees that existent weapons should keep their keyword, then we can discuss further if putting them in line with Essence Interrupter, Frostfall and LDV is a good thing or not.
Personally I consider it more of a flavor thing with no major implications (like opening doors to new powerful builds). It means you will have to switch less vs immunes/very high AR enemies (mostly on upscaled PotD):
Frostseeker - helps vs constructs, big ooze, fire titan
Thundercrack - helps vs bog lurkers, skeletons, death guards, some vithraks, most constructs, warden/tyrant of decay, Hauani, Ukaizo guardian, Auranic
Dragon's Dowry - helps vs bog lurkers, skeletons, tyrant/warden of decay, Hauani
Sun and Moon - helps vs bog oozes, some grubs, some panthers, Hauani; it makes also its draining ability less useless
Grave Calling - helps vs earth blights, eotens, rathuns, menpwgras, flame nagas, Hauani, magma dragon, Fire Titan, Soul Collector
Hel Beckoning - helps vs some ogres, constructs, Belranga
A special case is Magran's Blessing shield - it already does crush/burn damage but it has no keyword attached to it...