That's not very true. People would normally want their OS drive to be fast so everything is a lot snappier and it's for the same reason why people buy Raptor drives when SSD hasn't existed. If there is a cheap and good method to store the whole OS in RAM permanently without losing data when you power off, many people would be doing that as well. You're paying the money for the speed which SSD's can offer, not the space. A typical setup is to have the SSD storing your OS, programs, etc and all other things in a conventional 1TB drives as storage/backup.

If you have not tried a properly configured SSD system, it would be very difficult for you to understand how good/fast is the SSD. You need to understand that the current bottleneck in most modern computers are I/O devices, not your CPU, RAM or board. By having an SSD, you are actually closing the "bottleneck" gap. For example in my PC, I can start Office applications in 1 second, Photoshop 64 in 3-4 seconds, boots up Windows in less than 15 secs. Far Cry 2 game loading is also easily 50% faster compared to my previous Raptor RAID-0 setup.