It’s always interesting when a star of a highly rated show leaves. Anytime in any occupation you can have some job security take advantage of it. Of course these roles are played by real people who have lives to lead and people can get burned out.
However you see soap opera stars playing their roles for over 30 years and they are still going. Perhaps they know something about longevity.
There are some high profile exits such as Matt Smith of Doctor Who, Cote de Pablo of NCIS and many others who have heeded the call of other opportunities.
Many people have invested their hearts and souls into these characters. They live their lives vicariously through these people who do things extraordinary. To me its OK to mourn, its a loss and some folks take it hard. Exits if done right can soothe the sting of a actors departure. If an actor is killed off violently the show risks losing that fan. It will be interesting to see how characters are resolved down the road.