DS9's guest characters were powerful religious icons, powerful warlords, former spies, etc. They were inherently more interesting characters to begin with.
Excuse me but NOG, was one of the best developed characters in all of Trek and his arc has him going from loser trouble maker hanging out on the Promenade and nephew of Quark to being the first Ferengi in Starfleet and an invaluable member of the crew. He goes from nothing to cadet, to ensign to Lieutenant in 7 seven years. Thats more development than Harry Kim and Nog was NEVER a member of the main cast.
Morn, a character that never spoke, actually got character development and got to play an important role during the war.
Thats called having excellent writers that actually understand and want to work with the cast of characters that they have.
Voyager could have done the same thing. The Maquis were rogues that we know also included mercenaries and all types of interesting folks. Hell, the Enterprise, the flagship of the Federation gave us Barckly...a holoaddict with social dysfunctions.
Look at the characters that they COULD have used...
Carey...who disappears at the end of season one only to reappear and be killed off 6 years later (which was downright insulting)
The Equinox crew
The uncooperative Maquis
essentially they could have done ANYTHING other than what they chose to do...which was to down play most of the main cast and largely avoid secondary characters.
Whats really BIZZARE is that they did that and then had the nerve to do that stupid Ensign Lindsay Ballard episode later on...about a supposedly beloved member of the crew that "dies" yet mysteriously turns up and reignites a relationship with Harry Kim. Imagine how interesting or dramatic that episode would have been had it featured a character that we'd ACTUALLY SEEN BEFORE!!!! I consider this episode a prime example of Voyager epic fail...a story that should have been more emotional but wasn't because the writers were lazy all along.