That's a good question and I have the impression that it's not such a widespread problem but if you use your machine to make a living you surely wouldn't want that to happen to you, right?

Actually my point isn't about the necessity of BD in the new iMacs, I was just responding to the user who pointed out the HDD solution for backups. Of course I already use them but from work I got this habit to use DVDs to back up as I feel much more confortable this way, and I think that the BD drive option would be very useful to me.
If it won't be added then I'll be fine anyway.