Aren't torsion bars superior in many ways? Don't Porsche's use them? It keeps the weight down low for better handling. It seems that coil-overs main advantage is getting more "race tuning" options and an opportunity to spend money and time.
I don't believe either torsion bar or coil over is superior to one another. Done right and setup properly they both can perform very well. The advantages that coil over will have is cleaning up the underneath of the chassis for headers, trans swaps, and ease of access. Both have advantages and disadvantages. It's all up to what you want to do with the car.