Disagreed completely, I was very glad to have used that lockstone. I fail to see how it would have been different in the other build too; you could also use the torch to illuminate the area either way? This light from the lockstone makes the annoying enemies far easier to handle. They'd be terrifying without the lockstone.
Oh I was only let down because I used the stone long after I had completed that area, thinking there was treasure in that lock I passed up. Had I used it on my normal progression, I would have felt differently. Just pointless after all the treasure was looted and the boss dead.
The lighting effect is really cool though, and makes the top level run easier without a torch.