It's not very apparent in the video, but more apparent in real life, I have been to that track numerous times, and will have hopefully have the oppertunity to slide there after the olympics are over, the walls create quite a deep trough, and where the slider went off the track is NOT a technically hard section.
All sliders when they fall 99.99% of the time end up just sliding along the base of the track, since the majority of the time you are pressed into te ice surface at somewhere between 2-6G's. Netting is not an option due to the entanglement hazard, as well as it would make it impossible to do track prepararation. What will probably be done in this area is a lexan extension coming up off the wall which is installed on other area's of the track, in the more technical area's
Padding would have not have worked, there are just too many poles to protect, as well as at 140kph padded vs unpadded wont make too much of an impact.
The IOC does not have any input over the design of the track, this track has already had upwards of 10,000 passes down it, both in practice and in World Cup competition, gaining a reputation both as the fastest track in the world, but as a technically challenging track as well. Assigning blame at this point is pointless, but at this point in time discussion points to a pilot who unfortunately didn't really have the experience on difficult tracks, the comparison I have heard made in relation was he was a AAA player who got dropped into the NHL right before the stanley cup because someone had room on the team. Pilot error and inexperience is pretty much the rumored cause in this case.
Just to put in context how safe they believed this track to be, is that every 5th grade student in the Whistler area as part of a "olympic experience" project was invited to come and experience luge and hundred's of children attended with the worst injury a sprained finger. These kids did 3 runs each starting frther and further up the track, and most were finishing with speeds at up to 90+ kph