And more importantly than that, it just wasn't an important episode with severe consequences. With the exception of a new alien species being introduced, this episode didn't have a large impact on the characters or the series as a whole.
But isn't that the case in tons of TNG episodes and some DS9 episodes too so why should Voyager episodes get marked down for it? There are standalone episodes in Trek that are just there to entertain us using the characters and surroundings we know. "Hard Time" was a fantastic DS9 episode but the events in it were never discussed again and didn't seem to affect O'Brien out of that episode but I definitely wouldn't mark it down for that.
And regarding Phage, I did feel it set more of the scene for Voyager in the DQ. It gave us Neelix's mess hall, the Viddians we, Kes was offered the position of a trainee nurse, and it developed the personality of the Doctor and Neelix.
As for why I like the episode. Well first of all I think it developed the characters of Neelix and the Doctor further in a fun way, I enjoyed their interaction a lot.
I also love the scene in which the Vidiians were introduced and Mulgrew's acting was superb in that scene. The Vidiians themselves were interesting and a unique villain to Trek, 3 dimensional and sympathetic. Can we outright condemn their actions when they're doing it just to struggle to stay alive?
Overall, its a strong episode and not simply just a "things happen oooh sci-fi" episode. We got character development and it set the stage for future events such as Kes training to be a nurse, Neelix running the mess hall and the Vidiians re-appearing.
I feel the same way about Jetrel too, another strong character episode that tells us more about Neelix's tragic backstory and I'll be damned if Ethan Phillips wasn't one of the best actors Trek ever had.
But I do think that I will enjoy Voyager even more if I can go into each episode without such high expectations.
Definitely, I think you're trying to compare a few Voyager seasons to the whole Dominion arc or something.
I personally take Voyager on an episode by episode basis and evaluate just how much the episode entertained me or touched me. Its only when I take a step back to evaluate the show and ask "how much did this show live up to its premise/develop its characters" etc etc that it takes a hit.