Someone brought up Lindsay Ballard a few posts ago, and that is an excellent example of where VOY messed up. Rather than have a long line of recurring characters, who would have pretty steady work for seven years as they popped up from time-to-time (and didn't do a Carey), interacted with the mains, who we got to know and care about over time, they just created her and expected us to give a damn about her from the word 'go'.
Had Ballard been introduced in S1 (maybe even the second or third episode) as an Academy friend of Kim's, who he was attracted to but felt guilty about due to Libby back home, who came on the occasional away team or what not of the next few years before she was killed off, her death and its impact on Kim would have been something they could have used.
The lack of continuity really screwed up VOY, I think. Given their situation, you could have had just about every crewmember named and given a duty station, to be brought out and used when needed, but instead all they did was give us more of the Seven and Doctor Show.
Such a shame really.