Originally Posted by dbrier
The short answer is MONEY.
As a previous poster mentioned, it might also have to do with the fact that a 6.5" wide wheel is the ideal width for the 205/55r16 tire that Subaru spec'd.
Of course, I think most of us would agree that the RE-92 HAD to be a Money-based decision, so perhaps it was the Money decision on the tires that resulted in the narrower wheel size.
As to why they didn't do this on the GC-era cars, well, it was a relatively limited run, and they already had the 7" wide wheel, which was a better match for the 205/50r16 tire they were putting on the cars for the rest of the world. Ironic as it may seem, they probably didn't want to spend the money to create a narrower wheel for the old RS, so they slapped the cheapo tires on 16x7 wheels. In a weird way, the reason the RS got 7" width was probably to SAVE money, while the newer WRX got a narrow wheel to better-match the stock tire.