its been a while since i read the lore from the game.
but from what i remember the Eldan who where chosen to be part of the creation of Drusera, where actualy chosen because of their status as the greatest minds of the Eldan, its sort of like chosing the best human scientist or athlete for a mission that is about traveling to Mars. Also, based on some other things from the game, there seems to be hints that the accident that created the Enity was caused by one of the chosen Eldan who was too pridefull to give up his life for the creation of Drusera and thus tweaked on the machine that was going to create Drusera so that his personality would “hopefully” remain.