oh I thought he was intentionally using "Marine corpse" as a pun to suggest he thinks Marines are useless and just die easily.
Anyway, I LOVE Marines, I just think they're really cool in real life and its kinda spilled over into Civ (same for submarines and ships). I love having them around, they can be very useful.
If you've got a fleet made up (say a fleet of a Carrier, few Battleships, couple of destroyers etc) it doesn't hurt to have a transport or two filled with Marines, just incase you see an opertunity to use them, and obviously they're good for those one tile island cities that annoy everyone of us. A Marine Army is awesome, very useful in my opinion also
And also, they're quite good if all else fails for propping up some of your cities under attack, I've used them many times in that role.
As for paratroopers............. hmmm......... well this debate's been going on for ages. are they any use? I can't really answer here, I've never really used them in great numbers. by the time I'm at the paratroopers stage I'm either coasting to victory or fighting for my life.