Some of you guys are missing the point of the whole movie.
Though the movie had mutated creatures(not vampires or zombies) in it, it was not about the mutated creatures. Yes that was the driving plot, but the movie was more about his personal struggle to stay alive ALL ON HIS OWN. Note that he talked to the mannequins as if they were real people. He had a regiment for a reason, so he could stay somewhat sane. It's like if you got put into solitary and was told you'd need hear or see another person for the rest of your life. If you didn't figure out a schedule, you'd go insane. It became his obsession, and that's why he didn't run from them at the end. He was tired of running. Yes, he could of gotten in that coal shaft, but that would have been an even worse ending than what we saw.
I don't really expect people to understand what I'm talking about, because you almost had to be looking for the meaning behind the movie to even see it. If you take it at face value, you won't get a lot of what happened.
I do wish they would have gotten more into why the dark stalkers were actually still pretty smart, but that was another thing with the whole being alone part. He pictured himself as superior to the stalkers so he wouldn't be intimidated by them.
There's a lot of hidden meanings and stuff in the movie. I strongly suggest if you'd like to understand it a lot better, either read the book or get it on DVD and watch it with the commentary on. Yes this movie AND Omega Man were both based off the book "I Am Legend" written in 1954(I thought I said that already?).
I don't mean to offend anyone with this, just trying to help people understand the movie better.
-Magnum
PS - A friend of mine almost got one of those charred dummy bodies of the stalkers after the big explosion at the end. He was in New York when they were filming this.