(For purposes of this thread, great tv series = series the poster happens to think is great. Even if it’s The Sarah Silverman Program.
As everyone knows, Joan of Arcadia was the greatest tv show of all time. Even so, it lasted barely two seasons; no one seemed to want a series about a high school girl who had conversations with an ever-changing-and-very-subtle God. Toward the end of the series, I seem to recall hearing that executives at CBS were considering retooling it to ramp up the fantasy elements. This brought to mind the terrible, terrible image of God giving Joan superpowers ala Buffy the Vampire Slayer, going on quests ala Xena, and perhaps hiding throwing knives in her bosom. Such a thing would have been far worse than the series being cancelled, I think.
What other ways can you think of to destroy a series you love?