I think if the product itself is a web page, then the root www.domain.name needs to point to the product itself, not a description of the product. Imagine if I went to www.amazon.com and instead of the store, that page was a marketing template listing Amazon's business case and a few screenshots of what shopping at Amazon looks like.
IMO the only good reason to have a marketing/business-case landing page is if the product itself hasn't been built yet. Once the product exists, move the marketing page over to /about