A few things, I think.
For one, BioShock, while gorgeous and rich in story (or maybe richer than most), wasn't too complex as far as gameplay goes. I think that there will end up being other games that are looked back at as landmark as far as the medium goes. Two that spring to mind are Deus Ex and Prince of Persia: the Sands of Time (probably others too), but that is just my opinion.
For two, gaming hasn't quite made it to the big leagues yet, if you ask me. A tiny column in most mainstream newspapers isn't quite enough to convince a lot of people that this is legit, even if the cash being made should be enough to convince anyone that gaming is not going away anytime soon. Digital gaming is more and more being accepted and used in conjunction with other forms of art, but the transition is slow.
Third, not every medium evolves and is accepted at the same rate. Comics have come far from their 50s (and earlier) roots, as far as being accepted as legitimate forms of "art" but even they aren't universally accepted to this day. Art is probably the most subjective thing in existence and it may take games longer than other media, though who knows.
Forth, gamers act like spoiled children sometimes and online experiences do little to help foster that games are "mature" enough to be considered art, though a lot of game content doesn't much help. I mean, Duke Nukem is still on its way, isn't it? While the majority of gamers might be older, it is the noisy dickheads and the childish gorefests that garner the most attention and that does us all a disservice, unfortunately.
Regardless, asking why any game hasn't changed the industry, one that is already so deeply rooted in commercialism, doesn't make a lot of sense to me. The film industry has and does some amazing things, but the majority is formulaic, bland nonsense, and this commercialized "art" form is no different. Why would it be? Risks cost money and these corporations are not in the business of losing cash or they'll end up like Tim Schafer: lauded for making amazingly different games, and not making a whole lot of money. Unless the industry reaches stagnation to the point of losing a lot of customers or else someone makes something radically different that gives them a practical license to print money (i.e. the Wii (sort of)) don't expect it to change.
I imagine as Game Studies establishes itself more and more a legitimate subset of Communications in academia, there will be less and less debate over the acceptance of video games. Right now it is established but not quite centralized, so we have a way to go (remember that Communications as an academic discipline is only forty or so years old). The media will follow soon after, and have started already.
These things always take time.
