The dramatic need (ie. in the scripts) for a 'saucer seper' was negated by Voyager's ability to jettison the warp core and then re-integrate it, as we've seen in a few episodes. If, indeed, the primary reason for seperating the saucer is in case of a warp core breach. As opposed to, you know, maybe Neelix deciding to take it for a quick joy ride one night while the crew are all suspiciously asleep after he served them some of his new soup in the mess hall, or something. It could happen.
I mean, if you can jettison the core, and the ship doesn't have families on it anymore, then there isn't really a need to a saucer seper is there? Unless it was for purely tactical reasons, like we saw with the Prometheus in "Message In A Bottle". Of course, that doesn't mean Voyager can't
seperate. But I'd argue jettisoning the core is easier. Except on those occasions when the jettison fails and the core stays clamped in the engine room. If that happens then they're pretty much screwed.