Hey Postal,
I think that the problem isn't so much that the mounting point is weak, but rather that the hole in the metal bracket that attaches to it doesn't line up with the mounting point on the bike, and people tend to put a lot of stress on the plastic by forcing it into place. ( at least I do ). Either enlarging the hole, or fabricating a new metal piece that lines up properly would solve this problem.
This is something I have meant to do when I have a bit of free time, but probably never will. Oh well...
Steve