I can understand it. WhM is a relaxing class to play. It needs less of the constant focus that a dps does and that's appealing for newer players. It's fine to enjoy the current healers.
However, when you learn your WhM and your team learn the encounter (which doesn't take long) you soon learn there's no further room to improve. Every fight is Dia, Glare, Glare, Glare, lily for raidwide, Glare, Glare. You start longing for those messy runs to really test you or make you feel your skill contributed to the run. There's nothing to master, where dps have so many tiny factors that can push you that bit further. That's where experienced healers get bored.
