Achievements are measured in different terms. For a scientist, winning a Nobel prize might be the zenith of his achievement; for a player getting his picture in the cover page of Sports Illustrated might do it. For designers, having your design worn by a celeb-that to a royal princess, would mean a great deal.
Nobody is starting a ticker parade to celebrate this, a small acknowledgement shouldn't be criticized like this. Instead of suppressing the display of joy, why don't you just be proud of the fact for a few minutes that the accomplished designer was from your own country?