I am not trying to excuse the unlatched cowls, just passing my opinion on the challenge of seeing the latches in place, due to the ergonomics of the situation. This incident will make a good case study for Human Factors training, how did more than one set of experienced eyes miss it?
Fortunately, this incident resulted in no injuries. Another (infamous) incident of incorrect latch fastening (on a cargo door) resulted in several hundred deaths (the THY DC10 that crashed outside Paris.)
Sadly human errors are difficult to eradicate from complex systems.