Nicely put...
The problem as I see it with battle clerics is almost exactly what Impaqt is saying. With DDO (aka D&D) most players look for a cleric to help heal the party, cast some buffs and occasionally use some offensive spells like blade barrier, etc... I personally have played both roles as a cleric and have chosen to now play only the healer role in most cases.
My experience as a battle cleric was actually very good through maybe level 13 or 14. I could heal the party effectively which I always took as my priority and I could melee pretty good along with some of the nice offensive spells clerics have. What I found as my "battle cleric" gained in level beyond 13 or 14 was that I was havng to more and more focus on healing the party because the dungeons got tougher. So slowly the battle part of being a cleric became more difficult to play.
As a result I re-rolled my cleric.
My current cleric is what some call a "healbot" or healing cleric and I actually enjoy playing him a lot. My contribution to the party is greater because I focused him on healing and I enjoy the challenge of keeping a party alive at high level and on elite a lot. Some get bored by this class preference but not me as it is challenging in its own right. I still cast offenisive spells when needed but I let the melee types and casters do the damage for the party and keep them alive.
Summary: I found that although you can build an effective battle cleric when all averages are balanced out the party better benefits from a cleric that is willing to focus on healing the party. The reasoning for me is that "Fighters kill, Casters deal and Clerics heal". By that I mean although you can customize ach class and bend to your play style nothing kills better than a well build fighter, barbarian or paladin and a cleric built for healing can heal better than one not built for healing. In the long run its your playing preference but this is why battle clerics are usually not chosen over other healing clerics.