The Model 3's have a newer designed battery pack, likely able to take full advantage of the V3 chargers.
While the 100 packs went into production about the same time Tesla (Musk) first started talking about V3 chargers, it's likely the S/X packs and onboard charging hardware isn't able to (safely) charge as faster as the Model 3's. And providing the details of the relatively slower charging benefits for the more expensive S/X vehicles would have detracted from the V3 announcement.
It's also possible Tesla is continuing to do testing to determine how much faster they can push S/X charging without risking damage to the packs.
Even if our S/X 100D's don't get the full charging benefits that the Model 3's (and future Y's) are getting, we'll still benefit. Elimination of slowing for shared chargers will help significantly. Shortening the time of how long the Model 3's are using a charger will help significantly, because the higher volume 3's (and Y's) will be the highest percentage of vehicles using the Superchargers. And we'll hopefully get some boost in charging rate, which will help some, even if it isn't as much of a gain as what the 3/Y's will be getting...