Let's take a closer look at it:
was so bad it simply didn't deserve that second season and in all honesty it would've been better off without it (like that continuation of the 1st season finale that pretty much ruined the best episode that show had). Wasting resources on a show that doesn't deserve it, simply as an attempt to make up for canceling a good show is not a valid reason.
is an overall great show, but it had a scarily long stretch where it was so bad it was impossible to ignore its begging for a bullet in the head (similar to when nuBSG
was turned into a third-rate soap opera with the occasional space scene, just to keep up appearances). It was only during the most recent episodes that Fringe improved enough again to justify the financing to bring it to a satisfying finale.
Sarah Connor Chronicles
? I'm not sure you want to use shows as an example when they're merely an example for how a great premise alone is still useless when their scripts need to be screened over and over again before an episode is even greenlit, because some writers are so bad they shouldn't be allowed to write for more than soap operas and reality shows. They only got somewhere decent when it was already way too late for it to matter anyway.
Then again, there's Touch
, which at least makes me believe that by now they were looking to greenlight some undeserving piece of crap to justify getting out if the science fiction business altogether if they want to.
A long history of canceling good shows isn't simply made up for by keeping undeserving ones on life support.