Are enough people not interested in Science Fiction shows anymore?

What has happened to the Sci Fi genre in televsion?  Through the years and even more recently we have lost some great science fiction shows due to low ratings.  Some include Buffy, Farscape, Firefly, John Doe, Invasion, Threshold, Surface, Stargate SG-1, The Dresden Files, Battlestar Galactica, 4400, The Dead Zone, and Journeyman.  Some of you may not agree with my selections of viewing and applaud the fact that those programs are cancelled.  There are still many more shows out there that I couldn't think of or you yourself may have been a fan of a show that is now dearly departed.

Granted there are still many great Sci Fi shows out there (like LOST and Heroes), I know because I watch them.  I also understand that not every show, no matter what genre, makes it.  Maybe it's just because I watched a lot of those shows that got cancelled.  It aggravates me so much when I get involved in a show that ends up in the trash.  Science Fiction offers a lot of mysterious happenings and events and questions that pose great story lines.  Such things never get explained or revealed if that show is gone.  Like:  Who actually was John Doe? Will Johnny Smith from the Dead Zone thwart armageddon? What will ever happen to that story line or character?  And a hundred other questions that the viewers will never have an answer to (some I couldn't even make up the answers for my own personal enjoyment).

LOST fans, what would happen (I have trouble even thinking it) if LOST was cancelled without all of the precious answers we so desire.  I don't know if I would be able to handle it without medication.  I take great pleasure in knowing that there will be a planned ending.  That is a luxury I do not take advantage of.

Unfortunately, I have at times reserved my right to not try out new shows, some were best to do so, some not.  But that's what TV on DVD is for!  What is to be the fate of future Sci Fi shows Fringe, Dollhouse, and Sancturary, to name a few?  I will try them out regardless, with hope.  But only time will tell if they survive public viewings and if I find myself once again without my Sci Fi fix.