When the doctor is with Janeway to resign his commission, Janeway is telling the doctor that she is responsible for the medical needs of this crew. You can determine that the medical knowledge is essential for this crew and its future survival. However, we know from the Episode Equinox that voyager has a second EMH doctor stored in memory without its ethical subroutines, which are easy to activate. See more
[the Doctor has decided to leave Voyager in favor of his singing career
I feel I've accomplished all I can here. Oh, there's the occasional medical mystery that challenges my programming, but mostly, it's become routine. And frankly, I feel my talents are often taken for granted. But when I'm standing on that stage performing, and I see those rapt faces in the audience... I feel I finally know what it's like to be made of flesh and blood.
Seven of Nine
You simply crave attention, applause, fan mail.
What if ...