Rebuilds are automatic. You replace the bad disc, it rebuilds. A layman can and is able to do this. How did you lose data here?
One problem is the time to rebuild the array. We have a few Raid 5 units at home, one of them is a 6tb Raid 5 setup (four 2tb drives), and as always happens with hard drives, one of them died. No biggie though, pulled out the dead unit, put in a new one, so no data loss. However it took almost two days for our raid unit to rebuild it's redundancy and get back to Raid 5 status. During that time we were vulnerable, if another drive failed we were toast. Now that's for a consumer grade raid unit, the Dlink dns-343, I'm sure the professional units work much better but we can't afford those.
I'm not saying a NAS RAIDS will always replace optical discs for backups, but it is absolutely, completely ridiculous to assume Blu-ray discs will be a popular method of consumer backup. It's just too painful, too expensive, and too limited. And it'll always be that way, even as the discs and burners become cheap. Optical media for home use is more or less dead. CD-Rs were ridiculously popular, DVD-Rs popular but less so, DVD-DL are pretty unpopular, and BD-Rs will be even less popular. It's just how the market is going.
Our 'cheap' 6tb raid ran us $280 for the dns-343, and 4 x $160 for the 2tb hard drives, so ~$920 for a cheap raid setup. I'm not sure how many people will go to the trouble of doing that, especially people that use laptops as their main and only pc's. 6tb may sound like a lot of space, but it really isn't once you start using an hd video camera, and I think hd video cameras are what will really push bluray adoption for typical consumers on laptops.
Blu-ray burners one day will be standard on all laptops and PC's, and eventually the media will be pennies just like it is for dvd-r's, so the cost will be moot. And I do believe that eventually everyone will be buying avchd video cameras once they hit the $300 range. At that point I think blu-ray discs will be a viable backup media because it will be cheap and easy to archive videos and/or give videos to others via disposable 10 cent discs. We're not there yet, my new laptop for example came with a bluray reader but not a burner, and bd-r's are still $1.50. But those prices will tumble, and blu-ray burners will become as standard on pc/laptops as dvd burners are now.
As far are reliability, maybe you are refereing to dual layer dvd's? I do remember hearing about issues with those, but single layer dvd's have been reliable as far as I know. I have some dating back almost 10 years and they still work fine, even the generic brands. The 25gb bd-r's are single layer as well so they should do fine. I admit to being a little more skeptical about the reliability of dual layer media, but I'm sticking with single layer bd-r's so I'm not worrying about it.
I personally think that blank 25gb bd-r's are a great fit for hd video cameras. A typical person can go somewhere, film an hour or two of footage, come back home and dump it to a blu-ray. I envision one day the process will be point and clip. Connect camera to PC, choose your menu style, and it will spit out a ready made blu-ray. They empty the video camera's internal memory, rinse and repeat. That's great for when you are on vacation, just bring a cheapo laptop, some blank bd-r's and your video camera, and video tape everything. I don't know about you guys, but I can easily video 1tb of footage on one trip alone!