I used to main Healer from 2.1 up until 3.2 and I refused to play anything else. My first real attempt at a dps was blm I started out awful it was really hard to keep up the rotation and I would drop Eno all the time. My blm friend at the time who was very skilled brung me to a dummy and had me sit there learning the rotation. After grasping the rotation we went to do a 24man and I was still dropping it after a few days I got mostly used to it.

Its mainly due to healers not having a set rotation so learning a rotation felt weird. After learning Blm other classes were easier to pickup like Bard, Monk ect.