I also heard once that they did it because they wanted to make sure they didn't have too many models under one nameplate. This would be important when two models from the same manufacturer would be close to competeing with each other.
Ex.1: Honda Prelude and Acura Integra.
Ex.2: Nissan Maxima (maybe 3rd gen.) and Infiniti G20.
They try to have one really good model for each style (Sport Sedan, Sport Coupe, Family Sedan, Compact Car, etc.).