Suicide is painless

[raven]

As a general rule, most comedies have happy, upbeat theme tunes. Take Friends as an example, which as everyone in the Western world knows, has the Rembrandts' I'll be there for you as its theme. And then there's Cheers, which has a theme tune more famous that the show itself. I loved it, because I grew up with it - even thinking about it makes me start humming it - "Sometimes you wanna go, where everybody knows your name...."
Which takes us to Cheers' spin off, Frasier, which has the happy and positively nonsensical "Tossed salads and scrambled eggs" as its theme.
All of this is leading up a point. Keeping all this in mind, can anyone tell me why one of the most sucessful, long running, and funny situation comedies in television history has a theme that runs, "Suicide is painless, it brings on many changes...."