Should you run ads?
This is like a product. It is renting out the real estate you have develop to offer other people's products.
Generally, I think ads reduce trust with developers. I'm against them as a general rule.
I believe you can always do better by advertising your own products and services laser focused on the developers that are visiting. E.g. solving the problems you know they have.
This must do better than generic niche-wide ads that you could add to the site.
That being said, if the business is in trouble or not working, or you don't want to develop products, then ads are a default product.