It's been quite a while now since I've played my cleric, but from what I remember the clerics were just fine. I don't see the point of removing their buffs. And playing a cleric has its difficulties, when playing solo or facing big packs of mobs.
If you want them to be more active in party fights, I would increase the mob's damages or speed attack rather than removing the clerics buffs. Healing is their purpose, not fighting. I feel like it's turning into the Discipline Priest class in World of Warcraft. It can be but then it has to be through a specific talent tree. Pure healers/buffers need to remain available.
I like the idea of nearby buff mechanism, that may add/remove some challenges, but I believe it'll be frustrating at some point. Maybe have a debuff that mobs put on players that have the same nearby mechanism but negatively on the party members if close to the affected player.