Why isn't there consumer RAID? Consumers seem to be buying a lot of cheap laptops lately. RAID would increase weight, heat, noise and power consumption as well as add $1-200 to the price of a $3-600 machine. The only selling point for that feature is "less likely to lose your data", which tends to imply that the standard model is likely to lose your data[0]. It's not popular because nobody would buy it.
[0] Of course, that's true. Still, it's not something the marketing department can say.
Not really. It would add the cost of one disk, which is around $30-$50 these days.
Now for laptops, space is an issue, and that's why SSDs were invented. Light, low-power, fast, and much more reliable than rotating disks. Perfect for laptops.
A RAID card is totally unnecessary. Software RAID is orders of magnitude faster than any disk it is going to be managing.
We aren't talking RAID 0+5 for your credit card processing database. We're talking RAID 1 so that when your disk dies from all the soda you spill on it, you don't lose your porn stash.
I use 3-way software RAID 1 for my homedir, and I don't regret it at all. It automatically fixes bad sectors when they occur (since the other disk has the correct data), and reads are 3x faster than they otherwise would be. And two disks can fail (and have), and I don't lose any data. It's great. For the cost of an extra disk, I would recommend the setup to anyone.
Trick I used to use was to have RAID 1 for my homedir, and then try 3 different mounts for /tmp. The first was RAID 0. The second two were trying to mount the two RAD partitions. It made /tmp larger and faster at the cost of a reboot if I crashed. Which seemed to be a worthwhile trade-off on a desktop.
RAID mirrors are a poor alternative to proper backups. They don't protect you from catastrophic file system problems, accidental deletion/corruption, flood, fire, theft, etc. I suppose for people on the road a lot, away from an IT staff, there is some benefit to having higher availability but in a world of <$500 laptops $30-$50 is significant.
[0] Of course, that's true. Still, it's not something the marketing department can say.