MeepoTheMighty said:
Really? I'm sure there are people playing Mutants & Masterminds, Farscape, Babylon 5, or whatever, who wouldn't have ever picked up a D&D book.
And, who says those people are picking up D&D books now? Is there any evidence that anybody (much less significant numbers of anybodies) picked up a non-D&D D20 System book, especially a licensed property, who had never before played D&D, and subsequently got into D&D? It seems dubious, at best, to me: if they'd wanted to play D&D before, it'd've been plenty easy to find the books, and plenty easy to find other players.
Secondly, it's not clear whether Gygax was speaking of the well-being of D&D or of RPGs in general. If the latter, it is unlikely that anybody who bought B5 D20 or Farscape D20 because of teh license tie-in wouldn't have done so if they hadn't been D20 System. In fact, there were probably a few sales lost to otherwise-non-gamers who weren't interested in also buying a D&D PH to play a game in the universe they love (and, being novice gamers, didn't realize that they could get around that "requirement").
Finally, if you simply mean that it's good that the people playing B5 or Farscape happen to be doing so using D20 System, whether or not they will ever cross over into other D20 System games (like D&D), i'd say that's dubious: if someone really is an isolated customer in the market (only interested in Star Wars, or B5, or Stargate, or whatever), then the fact that the game shares a system some other games is unlikely to make any difference, one way or the other.