General Discussion - The relevance of 古文?

As I see more and more of my 榜样们 here delving into 古文, I started wondering:

What is the actual cost-benefit-ratio? How much does it help for reading contemporary texts, trying to remember 成语 or getting a more substantial cultural background? How deep do you have to dig into it to draw value from it? I know it is helpful for the HSK but in the real world?

Are there any good web ressources out there?

And: When should you start? Not before the Advanced lessons here are getting boring? When you can read a newspaper more or less without a dictionary? Or earlier?