See- I don't see the WRX as "The car of the decade". Don't get it twisted, it's an awesome car. it basically started the import version of the muscle car wars. Prior to the wrx, you had the Honda Civic Si, and the Acura GSR/Type R, and the Sentra SE-R. The WRX comes along and changes it, and then we get the STi, the Evo, the MS3, the Ion Redline/Cobalt SS, the Caliber/Neon SRT-4..... it did a lot for the community to bring it more mainstream. Problem is, the success of the WRX can be attributed as much to the whole Honda JDM fad, and to a lesser extent, the DSM triplets. You get the American version of DTM. That feeds into the whole "tuner" thing. Honda has the right toys and plenty of them, Honda gets big. FAST. Suddenly, you have people looking for ways to go faster, and they turn to Japan, where these cars have been the bread and butter since before time started. (Take a look a boso to see how long the JDM tuner scenes' been around) About the time Honda gets BIG, the DSM kids figure out that big boost+AWD=fast. Honda kids fresh off the boat as it were, look at the DSM and decide they need a new weapon. About this time, Gran Turismo comes out, featuring a certian AWD Subaru. Then Subaru drops a bomb and gives it to us for reals. That prompts Mitsubishi (who had unwisely chosen to make the DSM into that stylistic piece of shit known as the 3g Eclipse) to start to play catch up, and they quick get the Evo through crash testing and deliver it to us a year later. Subaru, who by this point already has a HUGE lead, decided that being 2nd fiddle isn't good, and they slide us the STi. While all of this is going on Mazda decided to play a different version of the game, and releases the ms6. Too big for its own britches, it's NOT A success. But Mazda realizes that the DISI is a technological tour de force, and they decide to use it in a more practical application. The ms3 is born. The ms3 would be AWD but Mazda put the turbo on the wrong fucking side of the engine, and the downpipe gets in the way of the transfer case. BUT- it's a sales success... riding alongside the already admitted hit of the mz3.
So yeah, the WRX was a big influence, but the game it played was started a long time ago.