The X-Files is not just a creature-of-the-week show. It is not just a supernatural investigation show. And both shows you mentioned were off network air for decades (The cable version of OL was a contemporary) before X-Files premiered. Like I said, unique for its time.
It is unique for the time, I agree. I simply prefer Fringe. I wish it had gained a modicum of the popularity of the X-Files, or even Lost.