They are derived from a platform that also builds a standard hatch, but the RS3 is definitely more than a standard hatch I’m afraid. Also, anyone buying one for the drive will pick the saloon as its stiffer and wider tracked.
Secondly they DO corner quickly, bloody quickly as they have immense mechanical grip, what they do lack is driver engagement, feedback and playfulness. They are dull to drive at even remotely close to road legal speeds, they are dull to drive fast because you feel disconnected, but they do make a great noise and are incredibly capable. Capable doesn’t equal “fun” though.
Fun cars are typically ones that feel more raw, have the feeling of being on the edge of its capabilities more of the time (i.e. when driving SLOWER), and have something special about them (be that noise, roof-off motoring, driving involvement, or a combination of the above).
Literally anything can br made “fast” with enough money thrown at it, but that’s not necessary going to make a good, enjoyable, fun experience.