Indeed. I would have made numerous backups and put them in different safes (personal and at the office). It is such a shame that the original assets of one the best games ever created is lost... probably forever.
This is rather hard for to believe. I mean, they must have backed the stuff up to tape drives, cds and harddrives... but they still lost every backup?
There was a long discussion about this (about 3-4 months ago, and I think it was split between twitter and the message boards). If I'm remembering correctly, the upshot was that the BG1/BG2 art assets (3D models & textures) were backed up -- but they were unable to find the backup after a through search of the Bioware offices. Keep in mind that it has been ~15 years since the last time anyone looked or cared about these assets, so it isn't that hard to believe.
Were they stolen by an ex employee or something? Stuff like that just doesn't disappear into thin air.