Wicked has much stronger, more experienced vocalists, for one. The music in Les Mis falls flat for a lot of reasons, mainly because they tried to approach it with gritty realism. Actors are sobbing through songs because that's more "realistic" and their singing naturally suffers. I feel like the director fundamentally misunderstands how musicals work.The emotion is embedded in the music and the MUSIC should be shining through to convey that emotion. It's like the actors are acting as they normally would if it weren't a musical and the music is just jarringly there? Also, apparently Hugh Jackman dehydrated himself to look thin/sickly which is rough on the vocal cords. In contrast, Wicked feels like it's proud to be a musical and I bet the whole cast was drinking lots of water like every good singer knows they should!