Actually, his position is quite clear on the more-than-casual "fans" -- they're bad for the industry, because their willingness to buy crap sight unseen means that more crap is published than would otherwise be the case, and this crap services a market which is ever-shrinking by definition (since the crap drives away all but the hardcore). If there were fewer of these "fans" then products would have to sink or swim on merit. He's already expressed this position in this thread, and I agree with Eyebeams on it. I don't agree with his position on expectation though, and particularly where a legacy brand like GW is concerned (notwithstanding that I personally liked GWd20).
(Incidentally, such fans can in extreme cases be bad for professional sports as well; taking your baseball example, a team with a fanbase that will sell out the park and snap up merchandise regardless of on-field results encourages a non-competitive owner to deliberately lowball the on-field product because, hey, why pay big dollars for a good roster when you can make the same cash fielding a bunch of bums on the cheap? And yes, this does actually happen in the pro sports world and it's not good for the game(s).)