There are several good reasons for Voyager not to look battle damaged that have been mentioned in this thread: the damaged look wouldn't have fit the emotional tone of the show, dealing with battle damage would have taken up narrative time in a way that didn't fit the focus of the show, and we can reasonably assume many things were fixed offscreen. Not to mention that Voyager and Star Trek more generally have never been beholden to complete realism.
Additionally, at a time when digital effects were more expensive and the show relied on models, it was cost prohibitive to show Voyager's hull in different states from week to week.
Personally, I don't have a problem imagining some temporary damage to Voyager that isn't shown, just as I can get past the big spears tossed unceremoniously on camera in "Galileo 7" and the Horta that looks like an ottoman in "Devil in the Dark." I appreciate nice visuals and effects when I see them (and they are to be found in the original Star Trek, my two above examples notwithstanding); but I'm not one of those people who can't engage with a good story when the visual effects are limited.
Additionally, at a time when digital effects were more expensive and the show relied on models, it was cost prohibitive to show Voyager's hull in different states from week to week.
Personally, I don't have a problem imagining some temporary damage to Voyager that isn't shown, just as I can get past the big spears tossed unceremoniously on camera in "Galileo 7" and the Horta that looks like an ottoman in "Devil in the Dark." I appreciate nice visuals and effects when I see them (and they are to be found in the original Star Trek, my two above examples notwithstanding); but I'm not one of those people who can't engage with a good story when the visual effects are limited.