Ok, let me redefine that as "a job that actually matters on a space adventure show." After all, scrubbing the decks is a real job on a ship as well...
...but that doesn't mean that the ships janitor should be a member of the main cast.
Can anyone say with complete sincerity that Troi's job on the Enterprise was actually a worthwhile one and added anything to the series? The most interesting uses for Troi certainly didn't involve her sitting on some couch listening to Ensign Crybaby blabber on about their feelings, or convincing Data that he should explore his feelings of homicidal rage. Come to think of it, Troi didn't have a whole lot of good stories. There's not a whole lot you can do with a counsellor. About the most interesting stories she had was the episode she was altered to look like a Romulan and the episode where she took the test for command, and neither revolved around her listening to a crewmember complain about how their parents didn't hug them enough when they were children.
That's because of 80s writing, not because of a fundamental flaw in the character. The Sopranos shows us that a psychiatrist character is a very useful storytelling tool if properly applied.