One thing people outside of Paris don't realize is that the locks are not just on one bridge. There are two major bridges that have an overwhelming amount of "love locks." The first and most talked about is Ponts des Art, the second bridge is Pont de l'Archevêché near the Notre Dame. Below are some pictures I took late July of the bridge near Notre Dame. As you can see there are still tons of locks. The city has begun removing the locks but people keep adding more!
Even when the metal mesh is removed people quickly adapt to the new structure and find ways to add locks. It helps that there is always a lock vendor hanging out on the bridge.
I can understand the appeal of leaving a symbol of your love behind in the magical city of Paris. At the same time you are throwing keys into the river and overwhelming the bridge railings with added weight. I guess I'm just not a romantic. Luckily for the romantics the locks prevail.