Last time I read it, I did not find it challenging outside of some of the more obscure words used (particularly things like names of types of buildings and similar mundane objects), and my Kindle's built-in dictionary was able to define all of those in one tap.

As far as "for no reason", I would say that McCarthy's impressionist prose that meanders, leaves out some details while focusing on others, etc., is some of the best English language prose ever written. It's beautiful and conveys affect better than almost anything else I've encountered. All the "reason" I needed.