Priests, Imams, Medicine Men all are very rarely used by people. Infact, other than myself, I have ES, please consider changing the way these units work. Perhaps if they worked like a mobile Field Hospital, with slow but constant healing in a certain radius around the priest? Players would then be able to include these within their armies, instead of having to babysit them, devote control groups and spend precious attention on them. Thanks for reading.
I believe it's this need to babysit the healer units that's one of the main reasons for their lack of use. Automating their function will go along way towards encouraging their use.
P.S.
That reference to ES in my signature is not serious. It's an adaptation from an old joke about Blizzard North balancing methods, that talked about Diablo 2 instead of AoE3 and about the Paladin instead of the Dutch.
"One wants to be loved, failing that admired, failing that feared, failing that hated and despised. One wants to instill in other people some form of emotion. The soul shudders before emptiness and wants contact, no matter the cost."