Fine, let's just get right down to it:
Do you know what an idiot plot is?
Getting beaten by an enemy doesn't necessarily make you an idiot. Whether the marines were a crack fighting force or not, they thought they were, and had enough experience and reason to believe they could deal with the situation. That they couldn't doesn't make them idiots, it just makes them wrong. Somebody always loses the war.
Not always making the right choice is not the same as always making the wrong one.
If the writer had set it up that the marines were unbeatable, there wouldn't have been any movie, now would there? Nuke it from space up front, end of story.
And the writing? Better. No question. You read both scripts? Speaking here as a pro, Cameron's script was better, hands down, across the board, pick a spot.
Hey, you don't like the movie, you don't like what I write, no problem. You are entitled to your opinion, it's sort of a free country. Of course, if you can do better, have at it. I'm sure that the powers-that-be would be happy to see your stuff, given as how it must be so much superior to what's out there. Give it a shot.
Anybody can talk the talk. What else you got?