Well, but is this relevant for the question at hand? If somebody sees the D&D brand as valuable enough to base computer games, console games and films on this brand, that's some kind of advertisement even if WotC doesn't get any royalties from those endeavours.
Edit: I just looked at some games from 2002/2003 that I have. They contain this information:
"Neverwinter Nights, Forgotten Realms, the Forgotten Realms logo, Dungeons & Dragons logo, Dungeon Master, D&D, and the Wizards of the Coast logo are trademarks owned by Wizards of the Coast, Inc., a subsidiary of Hasbro, Inc. and are used by Infogrames Entertainment, S.A. under license. All Rights Reserved."
Wouldn't this point to a different company if the license wasn't given out by Hasbro?