There have been a stream of What happened to the Adventure game....for years, from inside and outside the industry....
here are several:
http://www.oldmanmurray.com/features/77.html
2000-09-11
Death of Adventure Games
2000-09-11
http://grumpygamer.com/2152210
May 22, 2004
Why Adventure Games Suck
Ron Gilbert
including one by Mr Gilbert himself....however, careful reading of these and others all over the place, many if not most just dont realize that THEY do not hold the sacred truth or establish it by writing or speaking......the modern critic in many fields seems to have got a serious God complex. WE the game players vote with our purchases and our wishes. And WE are the best place to see that Advventure story based games with nice settings and fun dynamic story lines and either action or puzzles or a combo of both still is way up there in the desires of the public. True, the MMO's right now have massive casual players, but from studying them, there is a high turnover as the grinding and faction bashing grows old for many....and the Gold Standard remains a good story in an excellent setting.