Sitcoms - and why they end the way they do

[Sephiroth]

Since I was a child I have always been a fan of sitcoms. Despite them mainly living for the "laugh about the moment" and being dorky most of the time they still have a plot and the characters that are developed.

However, no matter how often I think about the many sitcoms I liked, and still like for the aspects I loved long ago there is always the conclusion of the series themselves that pretty much ruins it for me. Of course a series must end but then it should at least end in a satisfying way for most of the characters and the audience. Just because a series loses some viewers and its decided to end it it does not mean you cannot write a more fitting ending.
Now of course some people actually like endings that I did not really like but when I think about the whole story, the characters and the show that they made I always see things that would need to be lead to an ending fittng for them that they actually deserve. I can end a show in a funny way and still I don't need to lose focus on the good things the characters have experienced until the end and even if a shows ends abruptly the finale does not necessarily need to look like that.

When it comes to this, there were three shows that I was not happy with how they have ended, those were:

Full House
The Fresh Prince of Bel Air
The King of Queens

And exactly one sitcom that I thought of as the best sitcom finale and while not being absolutely perfect, pretty perfect nonetheless, perfect especially because the main point of 10 seasons has been used to end the show.

Tell me your thoughts.