C.S. Lewis on Art for Art's Sake

"'How soon do you think I could begin painting?' it asked.
The Spirit broke into laughter. 'Don't you see you'll never paint at all if that's what you're thinking about?' he said.
'What do you mean?' asked the Ghost.
'Why, if you are interested in the country only for the sake of painting it, you'll never learn to see the country.'
'But that's just how a real artist is interested in the country.'
'No. You're forgetting," said the Spirit. 'That was not how you began. Light itself was your first love: you loved paint only as a means of telling about light.'" -C.S. Lewis, The Great Divorce p.80-81

While enjoying art for art's sake as an ultimate end of itself is dangerously idolatrous, don't writers, musicians, painters, sculpters who attempt art "only as a means of telling about light" end up producing kitsch? Doesn't this form of didacticism miss the primary point about art?