DC can't help that every book with Batman involved will be a great seller. And that a-list status sure hasn't crossed over to the sales for Marvel comics.
If I ran WB or Disney the sales of the actual comics would be a footnote in how I evaluated their success. The money made in movies and licensing is so much greater.
With comics an unsuccessful comic sells about 20,000-25,000 copies. A successful one sells 60,000 - perhaps 120,000.
The profit for paper comics must be fairly small after the paper/ink/shipping/comic store cut, so let's say they make $1 profit for each comic sold (probably a generous guess). Compare that with $100 million in profit (or more) for a successful comic book movie, not to mention the toy sales, book sales, and clothing sales that go along with it.
One Wonder Woman movie is likely worth a decade or more of Wonder Woman comic sales.
Disney would much rather have Iron Man be a big movie star than see his comics sell an extra 20,000 copies each month.