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'.
I don't see the real problem with this. I mean, TOS only had three main characters and was always pulling new crew members out of nowhere and expected us to care about them. No one complained then.
TOS was a show from the 60s, VOY was a show from the 90s and by the time the 90s came along, things like continuity and story arcs became more important, shows like X-Files and Babylon 5 made focus on contiunty and story arcs popular, so having Voyager ignore that makes it seem like it was behind the times in the 90s. Voyager seemed like an 80s TV show in the 90s.
If they'd openly advertised that VOY would only have a main cast of 3-4, and the rest would be secondaries, would there be as many complaints over the lack of secondary characters and how only a few got treated to development in the Primaries?
Heck, Xena only had 2 main characters and no one complained.