I find it funny that... (spoilers)

All the fans are asking for a second series of the programme. I loved the show, but I liked that fact it told a single story arc of Kevin coming to love Sarah and then losing her. Why is it people always want to drag a show out until it runs out of steam and becomes just an exercise for the writers. I hope it gets a DVD release because as a stand alone 22 part series it works well, perhaps it's best it got cancelled.