FishAk, that is purely your opinion.
You're exactly right Zap, the necessity of backing up a computer is purely my opinion. I'm sure it's your opinion also, and that you have a good backup system.
I'm also of the opinion that you should look both ways before crossing a street, you should wear a seat belt while traveling in a vehicle, you should wear protection if you shank a stranger, and you should maintain smoke detectors in your home. Not everyone agrees with my opinions listed, and they are entitled to make their own choice.
There is no indication in the OP's thread of an external drive, or any other backup solution. As you are well awair, another internal drive, while not a complete backup solution, is much better than no backup at all. As you pointed out, this is a family system, and not solely the OP's. If mom looses her photos, or dad loses all the movies he has edited and saved, who is going to get the blame if this is a home-built, regardless of where the fault actually lies? There is no question about whether or not the drive will die, the only question is when, and whether data will be lost. The data loss can be prevented for very little cost.
It is my very strong personal opinion that whichever computer is purchased, a backup drive must be acquired. But that's only my opinion. Some people are of the opinion that they don't need to wear a seat belt, and they are entitled to that opinion. Some of them will never have a problem.