Not sure I agree (for a change lol)
Audi have taken weight out of the nose of the S3 to try and make it handle far better. Sticking the 3.6 or even the 3.0 supercharged would have made it a drag car, great in a straight line, but terrible in the twisties.
I think they got it right with the S3, on track it's a pretty exploitable car:
http://www.youtube.com/watch#!v=zCf0B-a2vb8
http://www.youtube.com/watch#!v=3vCNsmamUmc
http://www.youtube.com/watch#!v=tmjsp0E_624
My car was stage 1 GIAC with a panel filter, a sports cat and non res centre with the OEM back box.
It never missed a beat. If it had a heavier engine in the car I just think it wouldn't handle anywhere near as well, and for me the best thing about the S3 is it's honest cross country pace - it may not offer a lot of communication and it may not sounds as nice as something with more cylinders, but it really can torment cars in the leagues above
I think the problem with these n/a cars for me is they way they are designed to appeal to the biggest audience, resulting in an engine with little character outside of the noise it makes... too linear a power delivery for me, the turbo just makes it more fun