I agree. It totally depends on the buyer.
I've driven the Mirage G4, the Mirage HB and the Vios. The Vios is definitely an upgrade over the Mirage. Long drives make me regret driving the Mirage (I have long legs, so the seat adjustment makes it awkward as i'm either too near the steering wheel or too far).
If i was the cash-strapped buyer looking for something to tget me from point A to B, then I'd go for the car with the 1) lower price tag, and 2) more fuel efficient. But if I want the most bang for the buck, I'd go for the Vios XE.