A TV show can fail to attract or sustain an audience for any number of reasons.
Normally, it's pretty evident; bad ideas and bad execution are still as rampant throughout the entertainment industry as ever. But now with over hundreds of channels to choose from and the rise of Internet entertainment to boot, viewers can afford to be extra-picky when it comes to whom they give their time.
As such, it truly can take only one bad apple to spoil the entire bunch. Regardless of how solid of a foundation for the show or how likable the rest of the cast may be, if one cast member causes too much drama, has a very different idea for the show than what is intended, or just plain doesn't feel like doing the job they are getting paid big bucks for, that's all it takes to convince a big chunk of their viewership to change the channel.
Now before anybody gets all panicky and/or uptight, let it be understood that nobody is perfect, nobody can be loved by everyone, and trying to please everyone ultimately winds up in pleasing no one. But in the case of the ten examples provided, it's pretty well evident how they are weighing their respective shows down by either alienating old viewers or preventing new ones from giving it a shot in the first place.
Sometimes, that damage can be remedied. Other times, the only solution is a kick to the curb. But either way, these people aren't helping, and if anyone tells the networks otherwise, don't believe it.