I have seen some photos. Latches were damaged in the strike, it starts just from the nose cowl all the way back to the reverser latches, with a number of holes through the structure.
As for picking this up on a preflt, if after you have looked at the fan blades you bend over while using the inlet cowl for a hand steady you can bend over far enough without lying on the ground and see all the way back along the engine. This is not the first time for a 737 to have a pod strike. Ryan Air had an identical event on two aircraft 2009 and both were missed by subsequent preflt.
I have watched the preflt being carried out by crew and it varies dramatically. Some walk from the nose around the engine across to the outside of the other engine back again like they are on the modeling cat walk without even looking at the aircraft, obviously thinking more about what's ahead of him or her rather than the importance of the task that he or she are carrying out alone. This task used to be backed up by a ground engineer and this was his sole task and he was equipped for this, no matter what the environment or weather conditions offered. I see crew without raincoats substandard torches (iphone torch) trying to complete a task that is often pushed by time, and sometimes the must get home attitude(defects always logged on the home leg). I see many crew finding themselves in this situation often without any immediate engineering support on hand as a result of a industry wide cost reduction. Two sets of eyes were always better than one. It's a race to the bottom reducing cost, until unfortunately we see a catastrophic incident.