Traditions are just that...a routine event carried on through generations. They have no "power" so cannot have an effect on a wedding. Just as it may be a tradition to decorate a Christmas tree in red and green, there is no law or tragedy that will occur if it is decorated in blue and gold one year. The something old, something new, something borrowed and something blue is just a way of connecting the past, the future, friends and family into a wedding.
If you're superstitious then I would say go for it. But in the last couple months I've been to numerous weddings and have found that not only are brides not doing the something borrowed thing anymore, they also aren't throwing the bouquet!
A lot of the wedding traditions aren't as old as people think. Even the wearing of a white dress, only goes back to Queen Victoria, who was the first bride to wear white. Yet people were getting married for thousands of years before then. It also became a tradition to have a chimney sweep at a wedding, yet who has this today?