DS9 had the entire Trekverse to pull characters from. VOY didn't have that advantage, and most of those external characters were ones with interesting background like Alien Leaders and Generals and Holy People and Alien Emissaries and the like. Not the kind of ones you can create from a bunch of random rebels.
Yes, I'm including NuBSG in there too because most of their characters weren't the random crewmembers of the Galactica but important political characters from other ships and colonies.
This is why the other crew should've either been Romulans or random DQ aliens that were being held on the Caretaker's Array that the VOY crew took with them when they escaped. The kind you could justify having more interesting backgrounds to build characters from.
All the DS9 recurring characters I just mentioned, except for Keiko, never appeared in the franchise until DS9. So they weren't 'pulling characters from the Trekverse'... DS9
created those characters.
And while most of the crew and Maquis were human, there were other races on board, too. At least 3 Bajorans (Gerron, Tal Celes, Tabor), at least two Bolians (Chell and Golwat), and at least 3 Vulcans (Tuvok, Vorik, and a background female Vulcan). Plus half-Ktarian Naomi.
While DS9 did a deep dive into the Bajorans (for obvious reasons, as it the station was
inside their system), VOY could have done a few things with their Bajorans. We rarely got speaking Bolians in that era, so the Bolians on board could have been developed and given the audience a few looks into their culture. I will agree that the Vulcans were served adequately in VOY. (Tim Russ was fantastic.)
So VOY still had some good cards to play... they just didn't utilize the full deck.
Regarding BSG... are you serious?
A
LOT of their secondary and recurring characters were from the
Galactica herself, not 'important political characters from other ships and colonies'. A few examples...
Colonel Saul Tigh, Lt. Felix Gaeta, Chief Galen Tyrol, Lt. Anastasia Dualla, Cally Henderson, Lt. Brendan 'Hot Dog' Costanza, Lt. Louanne 'Kat' Katraine, Lt. Alex 'Crashdown' Quartaro, Captain Karl 'Helo' Agathon, Doctor Sherman Cottle, Lt. Margaret 'Racetrack' Edmondson, etc.
But sure... BSG never gave any focus on their crewmembers at all. Nor did we ever learn these characters names, ranks, and traits because they never uttered any dialogue or had countless scenes with them or were with the rest of the leads of BSG at all.
(Just so there is no confusion, that last paragraph was sarcasm. I know with some people and the internet, it's sometimes difficult to tell the difference.)