tension is the key to interest for people... at each stage in gets more exciting, they still get to see the top ten pose (they don't wanna see 20-25 routines that is boring), and by wiping the scores each round the judges essentially have to judge them 4 times and it gives a guy improving on the day the chance to move up...
This pretty much sums it all up.
Tension is indeed the key if you want to highlight the sporting aspect.
Also, there needs to be a way for the judging to be at least seen to be accountable and again, I suggest that the IFBB consider how the other artistic/creative sports deal with their issues of subjectivity and how their scoring systems are considered to be accountable (or not).
Surely it would be a good thing if the athletes (and fans) were able to know EXACTLY which areas held them back in the scoring. At the very least, this would give the appearance that bodybuilding was a legitimate competitive activity.