There are about 55,000 members of EN World. At first blush, that sounds really impressive! After all, 55,000 is more than almost any non-D&D RPG book sells! (White Wolf sells more of its major releases, and Mongoose may, but I'd be really surprised if anyone else does.)
However, this number isn't very useful. Of those 55,000, I would say far less than 1% post regularly, if at all - look at the names you see floating around the boards. Do you see 550 different people posting on a regular basis? MAYBE half that many post multiple times per week across the entire forum.
Now, consider that 55,000 is itself only a bit more than 1% of the overall D&D playerbase, according to the last WotC numbers we have. (FWIW, WotC staffers current and former assert that the number of players has gone up, not down, in the intervening years.)
In other words, even if we're generous and say 1% of EN Worlders post regularly, they amount to only .0001% of the D&D playerbase. One one-hundredth of one percent.
Finally, consider that there is almost never a CONSENSUS among the one one-hundredth of one percent.
I really don't see how data collected from EN World or any other message board of similar size could possibly be useful to a brand as large as D&D. :\