This thread has turned into the standard WRX vs higher cost of the STI. A basic premise is that you can not upgrade a WRX to STI specs cheaper than the factory ( unless you happen to own a wrecked STI ). Is the STI perfect, no car is. I think a lot of people mod for the sake of modding. Out of the box both cars are a very good package.
Potential buyers need to evaluate which car best meets their needs and wants.