For one thing, there surely would have been less games. Under the old system it would have taken just 48 matches to reduce 32 clubs to eight quarterfinalists. Whether this is good or bad is open for debate. What is pretty clear however, is that the more games you play, the more the cream rises to the top. In a two-leg encounter, anything can happen.
Individual episodes dictate winners and losers.
The better teams inevitably emerge. It's not my opinion, it's statistical fact. Of course, to establish what the best club in Europe in the 1999-2000 season really is, you'd have the top 32 clubs playing each other week in, week out, for a whole year. That, however, is obviously unworkable, so this is probably the best you can do. With the quarterfinal knock-out stage however, everything changes.