Well, Doctor Who is different as every few years the Doctor changes, and when it happens it's like a brand new series
But on games, specially RPGs, my mind can only remember things for so long. After 40 hours I'll have to go and re-read the journal as I probably won't even remember what am I doing there in the first place. And after 60 hours I'm already checking my Steam list to see what's next.
But TV shows are not that bad for a comparision though.
The following may contain very minor spoilers, but I try to keep it generic:
I don't watch Doctor who, but I have watched several TV Shows which basically were too long, which used all they had right away.
Of course this is also somewhat of a sickness of TV shows: Some of them are unable to keep it small. Which then means that the story gets more absurd with every season.
A good example is Supernatural. They started small (hunting ghosts, looking for father) and at some point they started to rescue the world from Evil X. And the next Season Evil Y shows up and wants to destroy the word. And of course this is nothing compared to Evil Z which shows up the following season and wants to destroy the world. Luckily they realized it themselves and managed to tone ot down a bit. But there are some Shows which just died that way. True Blood for example. It's a show which went on for much too long. The story in the beginning was great but it went havoc and absurd up to a point where almost everyone found out he/she was some kind of mythical creature. The initial setup of "Integration of Vampires into Society" did not play a role at all anymore.
I'd also explain that Shows like Breaking Bad ended because they ran out of believable, new stuff to do. If the amount of viewers are still acceptable and the actors are still on board, there is normally no reason to cancel a show as long as it is earning money. But it also might just be better to end it when it makes sense the most (now I haven't seen the ending myself, and I also don't know if there were other reasons).
Another TV Show related to the topic is "Once Upon a Time" which started as a show in an US Town where the inhabitants were figures from, well, Fairytales, who were cursed, put into "reality", unaware of being a fairy tale character. Now this certainly has some charme. But you can't hold it up forever and when this changes, the whole story, the whole setup changes. It basically becomes a completely different series. Much like if in shows like NCIS, Castle, Mentalist, White Collar and whatnot at one point they don't solve crimes anymore but do adventures in a jungle or get abducted by aliens. In the case of "Once Upon a Time" that would have been the point where the show should have ended imho.
While based on some real facts apparently, Fargo is a Show which does it completely differently and only keeps the story for one season alltogether. Each season is one criminal case, each season they change out the whole setting, actors and so on. It just keeps the name name of the show: Fargo. They are aware they can't keep the story going on for ever. So rather than making a storyarc spanning multiple seasons which might become unbelievable and boring, they just say one season-one story, which might just be the right thing to do in this case.