Hm, seems like you added that edit just now. The current FA20 in the WRX came after its debut in the twins. The boosted version didn't even exist at the time. From its inception, the people who designed the car wanted it to be NA. You're acting like they could have just dropped a turbo in it and called it a day. The price would increase, as would RnD. The current price for the cars are similar to what the AE86 was back when it first came out when adjusted for inflation. The twins are not a car that will pull in massive profits. Last time I checked on the forums a year ago, they didn't sell very many. Those Prius tires are available on a select model in Japan, but it's not like it's a negative point. They offer low grip when pushed, and decent fuel economy when cruising.

There are theories that Subaru didn't want to eat WRX sales by giving the BRZ a boosted engine, but it's just a theory.

They still fulfill different roles. A person who looks to buy a twin isn't going to be looking for practicality lol. When I went looking for a new car, it was between the FRS, the new Ecoboost Mustang, the Hyundai Genesis, and a used 370z. All coupes with varying levels of performance and comfort.