I feel like part of this design issue is caused by player attitudes that frequently surface outside of static compositions. If the party wipes due to tanks repeatedly dying or healers not keeping up with the damage output you'll frequently get people flaming the tanks or healers over it. If the party wipes due to enrage caused by low DPS or a failed DPS check you rarely see people flaming the dps and instead see the whole "Oh well. I guess WE weren't good enough"