I do not mind seeing a main character being killed-off, if it serves the greater aims of the story being told and is not simply gratuitous. and the authoris should think even harder before bringing a character back from the dead. In 99.999999% of cases, I think dead is dead and it should stay that way. Looking at you, Spock.
Weirdly, I have a kind of 'resurrection criteria' for the setting. Data and Spock had their resurrections set up ahead of time. Likewise, I'd have had less problem with Janeway's resurrection if she'd been taken from another reality almost identical to our own or it was a Janeway created from a time paradox. If that makes any sense.