There actually was a valid literary point to Lois not knowing that Clark was Superman.
For about 50 years one of the main themes of Superman if not the main theme was the idea of the secret hero inside of us that others could not see.
Lois was the symbol-the human face-of all of that. She was the woman that Clark loved but whom he could not share his secret with.
It added a certain tragedy to the character. It also harkened back to classic and powerful myths about Gods in disguise.
When Lois knows Clark is Superman all of that is out the window.