Because, it's been repeated over and over ind I just don't like it as a plot device. I'd rather have a human for a main character rather than a computer.
It has not been repeated over and over, it has been in one game, Fallout 3.
Fallout 1 had a giant blob.
Fallout Tactics had 8 brains connected to a machine.
PL had a preserved brain.
But none of them has had a ZAX super computer as a main character.
Only Fallout 3 did.