Why does Cormac McCarthy not add punctuation and other grammatical structures in "The Road"?

Actually, his lack of punctuation and other grammatical structures (such as no semi-colons and few commas) has nothing to do with the themes in "The Road" specifically.  Cormac does these same things in all of his novels such as Blood Meridian, Child of God, No Country for Old Men, and Suttree, of which I have read all of them.  He said in one of his few interviews that when he was still in college he was asked to revise older writers work to make them more readable and clear.  He revised (punctuation, not content) writings by Swift by severely cutting out unnecessary commas and other forms of punctuation and was praised for it.  He said he always thought there was no reason for all of these marks to muck up the page.  He also said that if you write well enough and clearly enough there is no reason for quotation marks.  If you read interviews by him you will find out that people like to convey their own artistic impulses and ideas on him, but actually his writing is (despite the intense and esoteric vocabulary) fairly simple and straight-forward, which is what makes it so beautiful and rewarding.  So, as much as people would like to think his use of punctuation (or lack) has some deeper meaning, it is actually just to make the writing less convoluted and conjested.

I quote Cormac, "James Joyce is a good model for punctuation, he keeps it to an absolute minimum.  There is no reason to blot the page up with weird little marks.  If you write properly you shouldn't have to punctuate...yeah punctuation is important, so that it makes it easy for people to read.  I believe in periods, and capitals, and the occasional comma.  You really have to be aware that there are not quotation marks to guide people though and write in a way that it is not confusing about who is speaking." So really his writing style is about simplicity and has nothing to do with "The Road" specifically.