Why are pull ups or chin ups good or bad?
Well if you are talking about body building or developing the lat muscles, pull ups can be bad as they are difficult, therefore most of us will be thinking of getting ourselves up there opposed to working the muscles properly.
However, they can be good as a contradiction because the sheer work required to lift yourself will strengthen the back plus more. If you was to do say 3 sets of 3 really slow then it still will be good.
Another way they can be used is just getting the numbers in. This will be more plyometric and good for sports or martial arts by way of conditioning. I can see why bodybuilders may opt for options but truth be know that it is neither good or bad... It is simply bad or good depending on your chosen requirements.