That was a great read, and I hope it becomes a trend of adding consequences to your failures after Shadow of Mordor. I like the idea of some stealth games where enemies get tougher when you mess up, call in for reinforcements and wear armour (Splinter Cell). It just makes me more attentive and take my time with planning->execution.
My personal thing is, I'm not a fan of procedurally generated level design. I have to understand the layout all over again, rather than think of new strategies for the enemies I failed against.
About losing tension after the first time, isn't the unpredictable AI of the alien ratcheting it back up? I guess not in players' experiences, I have yet to play it (soon soon).