From: SuperAngelo128 | #022
short answer:
because everyone wanted to play Solid Snake one last time before the series ended
I'll buy that.
From: LeonhartFour | #023
But he did it for the sake of Raiden, who did have a lot to lose. And really, Snake isn't doing any of this for himself because he doesn't have much of a future. He does it out of a sense of obligation for those who come after him, which is admirable.
But that's the thing, you KNOW he doesn't die from that. You know he was at no point in risk going through that on top of him having nothing to lose. It diminished the impact. Yea he was doing it for Raiden, but why? Why the hell did Campbell drag him back into this mess when it could have easily been someone else? I would have cried manly tears if he went through the microwave after beating Liquid and then collapsing and dying at the end.