I have some new friends who are trying the game this season, and I think it would be really great if the free respecs lasted until level 100 or maybe even until you killed Nightmare Baal (I think after NM Baal might be more intuitive).
Level 50 just doesn't seem like enough time for new players to figure things out with the spec they like or how it works, so they end up feeling very punished around 80 or 90 when they realize they can't try other builds without having to relevel a new character.
Just a thought about quality of life for new players, I don't think it would mess anything up for the rest of us, but I think it would really help new folks a lot.
Cheers!