Are you kidding?
Law & Order
....and most recently "2 and a 1/2 Men's" future is in question without Charlie Sheen.
There are PLENTY of examples of shows that suffered ratings declines and issues due cast members leaving. It was one of the the main reason the creators of LOST couldn't kill off Jack, who was supposed to die first season.
There are more folks too consider other than women when thinking of getting rid of Garret Wang. Wang is the first Asian actor to be the the main cast of a Trek series. Having Wang in PEOPLE magazine not only has the potential to bring in women but the growing Asian American community as well. It's potentially more controversial to fire an ethnic actor on a show that's supposed to promote equality than it is to swap out one blonde hair, blue eyed actress for another.
You missed the point entirely. You toss out a list of shows that lost their KEY stars and compare it to what I'm saying? In my post I said 'perhaps if he was some kind of pivotal character
' which he was not in any shape form or size, yet most every show you use has key characters leaving:
Charlie Sheen - star of the show
Duchovny - star of the show
Anderson - star of the show
CSI - Grissom was the star of it despite it being an ensemble.
Spin City - Fox was the show! The show was made for him after his stellar performance in An American President.
Law and Order - Which character? Which season? They had so many exits over the years I lost track. So please pick one and keep in mind that this show ran for just shy of 20 years. Figure a two year decline toward the end before cancellation and there is not one character that could have possibly caused some huge decline given there were so many cast changes over the years.
Harry Kim would have not been missed if Kes wasn't missed. Kes played a larger part in the show while kim was on the sidelines. He quite possibly had the least screen time of all the characters. So we're talking apples and oranges since I did say provided they weren't a key character.
Edited to add that you also have not figured into the equation that most of the shows you listed were fairly big hits. Voyager was never a huge hit. It wasn't even on a major network.