I leveled as Prot on my pally, and yeah, there isn't much to spend holy power on in dungeons. Hammer does enough threat on AoE pulls, and I do big pulls, like, 3-4 packs at time sometimes. Word of glory is just a better use. It's not that I don't trust the healer, it's that its more defensive. Overhealing creates a bubble, so even if im at full HP I will sometimes use it. I can understand why it annoys you, but overall i'm just trying to be a bit more helpful and relieve a bit of stress on you for my huge pulls. And besides, tanks aren't the only person who need healing. =)