An extremely overdone literary topic - the life and adventures of a man with the moral fiber of a drain clog. 300 pages about an awful man being awful. How universal. How literary. How worthy of praise.
This one works though. Babbitt is well written and you can relate to him, but not through his awfulness, which is painted as very boring and unattractive.
The point helps too. Lewis wants us all to be better. To not be Babbitt.