In a lot of Asian cultures brides, royal or not, wear a lot of heavy jewellery (you'll see this trend in Bruneian, Malaysian, Indian, Pakistani weddings, for example). It marks their status as a new bride and start of a new married life full of happiness and prosperity. Royal brides are understandably heavily bejeweled to not only reflect their status, but also that of their new husband and his family. It is all based on deeply rooted tradition.
I've seen pictures of non-royal Bruneian and Malaysian weddings and even those brides wear tiaras (some are real, some aren't).
I did note that the new bride, Princess Raabi'atul 'Adawiyyah, did not wear any notable new pieces. Both the ruby and emerald parures, for example, have been worn by several members of the royal family before.