From my experience with non gamer people...more people know what D&D is and has heard the name Dungeons and Dragonsm more than they know what Lord of the Rings is (before the movies). They might not know exactly what D&D is...but they know it is fantasy stuff. I'd think D&D was more popular within the general public than LotRs before the movies were out.
The only reason non gamers saw LotRs is because of the hipe and the fact that it was good enough to get people to actually say, "Go see this movie, it's good".
You kind of missed my point.
I conceded and expect that D&D as a product probably sells more annually than LotR, and has more visibility in the current pop culture than LotR does.
However, LotR has a huge track record in publishing- many editions in English are in print, and possibly only the Bible and Koran have sold more copies in the last 50 years. It is taught as literature in some schools.
Add to that the overlapping fan base- most D&D players were going to be interested in LotR- and you have an almost guaranteed hit...assuming you do it right.
And Hollywood is going to throw big money at almost any book with a strong track record like that, like the Harry Potter movies. Or the Bible.
There is no reason a D&D movie couldn't have received the same attention the LotRs movies had.
As mentioned elsewhere, D&D also has a track record of being blamed for a lot of things in the relatively recent past- the Satanic Panic of the 1980s, the assault that happened last week- that it just doesn't have the cache and squeaky-clean history that LotR does.
I think the thing that would make D&D successful is the fact there is so much material to work with and you can create a more original movie from that material. Movie makers are focusing their attention in the wrong areas and do more copying from other movies than just doing their own thing.
Its not the market for a D&D movie you have to look at, but the market for a D&D movie
in which setting you have to examine.
What is the size of the built-in market for Forgotten Realms? For DarkSun? Spelljammer? Greyhawk? Ravenloft? Maztica? Eberron?
Points of Light?
Now compare that to the built-in market for a fantasy novel or novel series written by one (or a few) author with a 50+ year history of being on sale.
Hollywood can look at Fafhrd & Grey Mouser or Elric and see potential in those much beloved novels. When they look at D&D, they have to look at which subset of D&D they're going to work with. The whole property is balkanized.
On top of that, some of the ones with the biggest followings are already somewhat "generic" in feel in comparison to established novels that Hollywood has already looked at.