There is a locked door guarding a required objective (destroying the cauldron in the library) that I could not find any other way to bypass except by picking it/knocking it. Lacking those abilities on my ranger I was forced to buy a bell of opening from the ddo store.

I'm very disappointed by that, normally if it's required that you get past a locked door there are alternatives available (finding a key, killing a certain boss, etc). This locked door doesn't seem to be doing anything special except ruining the quest experience for other classes that can't pick or knock.