The problem was that now teams are more confident going away, the home team in the first leg is encouraged to sit back, knowing that a more open second leg is in their interest. Add in that the second leg could go into extra time, and it gives even more advantage.No added incentive now for the away team in the first leg to attack. Expect more bus-parking in the CL knockout rounds, the main reason the rule was originally introduced back in the 60s.