Forgive me if this doesn't make sense. The windows of Amidala's apartment on Coruscant are made of transparisteel, according to Wookiepedia. How exactly could Obi-Wan dive through the window so easily. The clean-edged circular hole made by the assassin droid could not have weakened the structure that much. The simple explanation is that Lucas doesn't want people to overanalyze things, but I would be interested if any fan can provide a reasonable explanation based on what we know about the Star Wars universe.