The "coral ridge" that they hit is obvious in the many photos that are shown in an image search results on "aerial photo MV-Wakashio". I was surprised by the drone footage since it looks like the ship was perpendicular to the reef edge which means that the ship was heading directly at the large/populated island at near full speed but this was not the case. They were probably running parallel to the breakwater and hit this hidden anomaly in the reef and then wave action trapped the ship in this literal corner. Without tugs I don't think the ship could back out even if undamaged so I guess one outstanding question is whether a timely deployment of tug boats could have prevented the break-up of the ship.
The accident occurred at 8pm local time (16:00 UTC +4) so it was dark but the crew would have been awake. Tragic overconfidence.