Repeat topics are a bane to certain communities, it's a matter of taste.
To regular users, they're annoying, by discouraging the practice we get a cleaner place of discussion which promotes new, interesting topics.
The possible downside of this system is that users are referred to information that is out of date, in the near future we're going to be seeing this with regards to mobile porting and wrappers - luckily the more active members of the community are well aware of these nuances.
At the end of the day, the search function is your friend and should always be encouraged, which is the main aim of this policy - Scirra's severs can handle hundreds of thousands of user downloads, it's not a matter of bandwidth.