I am not saying it is ineffective at all, just saying that it does not do the same thing for all required muscles.
I am not sure anymore where I read it and how it was put but basically what it boils down to is to get better at an exercise, you simply have to do it. Period. All the rest is to assist you to reach that goal, but at the end you need to do the exercise.
I did lat pull downs when I started going to the gym, it was only when I really started doing pulls/chins that I could do more of them after some time. In July I could only do 2 chins in a row. I decided to make a pull-up bar in the basement and started doing more. I just do some pulls/chins whenever I can (started with sets of 2, now using sets of 8, sometimes over 10 sets per day). "Grease The Groove" the method is called. I could do 10 chins in a row last time I tested.
See here for more info on Grease The Groove:
http://www.dragondoor.com/articler/mode3/69/The lat pull downs improved as a result of that. Now I don't do them anymore at all since quite some weeks (they got too easy

and I moved completely to the SL5x5 program which does not use lat pulldowns)
Recently I started doing weighted chin-ups with a backpack and some sandbags inside.
Still need to work more on the pulls before going weighted there as well (chins are easier then pulls).