MaxTheReaper said:
Some people like to think.
This may or may not be an alien concept to you.
This is the answer right here. Well actually, more of a glimpse to the answer.
You see, Portal provided people with this false sense of cleverness, giving them a smug sense of satisfaction when they finished it. The witty dialogue from GlaDOS deceives the player into believing that there is a battle of wits going on, all the while they are spoon fed a series of rather easy puzzles where the solutions are clearly spelled out for them at each checkpoint.
In this, Portal is a marvel of game design, because it is less about the gameplay or puzzles, and more about the developers getting inside the players head and challenging their already petty ego.
This also means that players will identify with the game to the point of becoming fiercely loyal, taking any criticism about the game as a personal assault against themselves, and so anything other than a overwhelmingly glowing opinion of Portal will be met with hostility, because their pathetic little ego's can not take the crippling blow of the realization that they are nothing but sheep being led through a maze, like a mouse on a leash.