I dont know why you are complaining so much. Llorente can be effective tactically without scoring goals. Allegri himself says he plays him for tactical reasons and his role is not to score goals but more to draw defenders around him and be a reference point for our attack. In the 3-5-2, the wing backs are workhorses not because they should have a real offensive threat but rather because they stretch out opposition defense by their presence upfront and that makes life easier for our midfield and SS to poke holes and do the real attacking work. When teams ignore the wingbacks then the Licht and Asa used to become real threats going forward.
I imagine that llorente has a tactical role like that of our wingbacks in the 3-5-2 (I am not saying he is performing the same job I am only saying he seems to perform a tactical role) i.e. he is a player that has to be heavily marked so that he becomes ineffective as a target man and they also have to make sure he is not a threat in the air. In other words, he makes life easier for Tevez and is a target for long balls. I dont know if playing morata in a tevez like role would be better but we have been getting good results thus far so I am not complaining.