The point wasn't that the previous system was perfect or even better, it was that Blizzard clearly stated that they did not want a "best" build to be available, since they saw how much it ruined diversity in D2 (everyone using the same two skills out of god knows how many etc.). That's why I hope they balance it properly, since I understand why they removed the point system.
What I mean about killing diversity is that every single wizard/barb/WD/whatever will be exactly the same stats-wise if there's no player-input. This means that if the skills aren't all equally useful and powerful, the powergamers (which is frankly most of us when it comes down to it) will simply decide to not use it in the end.
I'm pretty sure they'll do a good job but it's always possible a completely broken build will be made, since no one can play through the game the many thousands or even millions of times the combined users will.