Actually, thinking about it more, it wasn't even so much the stories or the acting or such that made the show fall mostly flat. It was simply the overall background atmosphere. Voyager was just too clean.
The uniforms were rank and file neat. Bulkheads and floors were sparkling whole and unscratched (not to mention the most completely bland color scheme possible). Repairs happened at the snap of a finger (or at least by Janeway's second snap). You never heard complaints about food shortages or berthing crunches, replicator failings, or power conservation blackouts. Nobody missed home for more than five seconds, and everyone got along peachy keen after five minutes.
For a ship lost 70 years from home, life was just too easy.
Easy answer: Money. UPN didn't want to put up the money needed to redress the sets allt he time to show either the newt tech incorporated, or battle damage.
Also, they didn't want to put up the money of making new VOY ship mdoels to show damage or tech changes (Back then it was more expensive, not as easy as BSG does it).