I agree with you that it should be a good thing, but I've given up on trying to predict the effects of LME levels on copper price. About a year ago, the levels were as low as they are now and it didn't seem to do a thing.
It only makes sense that a shortage in warehouse levels would eventually drive a price increase in copper, but historically, I haven't seen this happen. Then, you can factor in the overt manipulation of the market by China, with speculation of them flooding the market with their stockpiles - copper no longer being allowed to be used as a hedge for borrowing. I'm not a conspiracy theorist, but I do feel that the price of copper is being deliberately manipulated and depressed. That being said, I think it's one of the best and safest commodities to be invested in long-term.