It might be difficult for a seller to actually determine what constitutes complete when it comes to older boxed pc games. I have some with so much stuff that I didn't think came with it. So yes, pictures are more important than a description so a buyer can see what they're getting. Having said that, if I have a box and a manual with the game itself that's complete enough for me. I don't need registration cards, envelopes, advertisements, bits of plastic wrappers, etc.
I do like the catalogs that come with some games like Lucasarts, Broderbund, or Sierra. Those are fantastic.