TNG and DS9 represented something of a golden age of the ensemble cast in Star Trek. Beyond that though, it was the point at which Trek had the most secondary characters. These were not just guest stars of the week, but where characters the helped to round out the crew while not formally being part of the main ensemble.
TNG had,
Chief O'Brien
Keiko O'Brien
Guinan
Ensign Ro
Alyssia Ogawa
Reg Barklay
DS9 had enogh recurring characters to make a second series
Lt Cmdr. Eddington
Nog (who got more screen tiime than Jake)
Rom
Leeta
Weyoun
Damar
Dukat
Kai Winn
Bariel
Fem. Shapeshifter
Keiko O'Brien + Molly
Cassidy Yeates
Admr. Ross
Gen. Martok
and of course GARAK
(I'm going to consciously ignore Vic Fontane)
DS9 managed to have all of these characters while (some of whom are better developed than main characters on either Voyager or Enterprise) while maintaining a fully fleshed out 9 person main cast.
Voyager started out trying to have an ensemble show with numerous secondary character
Seska
Lt. Carey
Ensign Souter
Lt. Wildman
Vorik
Even the weird guy that ended up being a traitor...
Then the writers dropped all of them and started kicking main characters to the curb as well. What's worse is that these mildly insteresting secondary characters would in effect get replaced by...Naomi Wildman and the Borg Kids
(this is the point that Voyager formally became DisneyTrek) 
Enterprise dropped the ball completely. Not only were half the gast being systematically ignored, but the show really did not have secondary characters. Shran, Admr. Forrest and Soval were more like recurring guest stars in the mold of Q or Lawaxana Troi.
What makes makes Voyager and Enterprise's lack of secondary characters so odd is that the very situations at the core of the series were perfect environments for such characters. They were ships largely isolated with a set number of personel. Indeed there was an episode of Voyager that could only have been helped dramatically had they had secondary characters. I'm not sure of the episode, but I think it was in season 5 or 6 and featured the "return" of a member of the crew that Voyager was forced to leave behind. The drama of the episode was completely lost because it was about a character that the crew apparenly all knew VERY well, but we the audience had NEVER seen before.
The creatively bankrupt writers on Enterprise obviously thought it worth while to create a characters known only as "chef" who not only was never shown on screen, but they did not even bother to give a name.
I'm just wondering why they abandoned the entire notion of secondary characters especially on shows where such characters might have improved the dramatic situations?
TNG had,
Chief O'Brien
Keiko O'Brien
Guinan
Ensign Ro
Alyssia Ogawa
Reg Barklay
DS9 had enogh recurring characters to make a second series
Lt Cmdr. Eddington
Nog (who got more screen tiime than Jake)
Rom
Leeta
Weyoun
Damar
Dukat
Kai Winn
Bariel
Fem. Shapeshifter
Keiko O'Brien + Molly
Cassidy Yeates
Admr. Ross
Gen. Martok
and of course GARAK
(I'm going to consciously ignore Vic Fontane)
DS9 managed to have all of these characters while (some of whom are better developed than main characters on either Voyager or Enterprise) while maintaining a fully fleshed out 9 person main cast.
Voyager started out trying to have an ensemble show with numerous secondary character
Seska
Lt. Carey
Ensign Souter
Lt. Wildman
Vorik
Even the weird guy that ended up being a traitor...
Then the writers dropped all of them and started kicking main characters to the curb as well. What's worse is that these mildly insteresting secondary characters would in effect get replaced by...Naomi Wildman and the Borg Kids


Enterprise dropped the ball completely. Not only were half the gast being systematically ignored, but the show really did not have secondary characters. Shran, Admr. Forrest and Soval were more like recurring guest stars in the mold of Q or Lawaxana Troi.
What makes makes Voyager and Enterprise's lack of secondary characters so odd is that the very situations at the core of the series were perfect environments for such characters. They were ships largely isolated with a set number of personel. Indeed there was an episode of Voyager that could only have been helped dramatically had they had secondary characters. I'm not sure of the episode, but I think it was in season 5 or 6 and featured the "return" of a member of the crew that Voyager was forced to leave behind. The drama of the episode was completely lost because it was about a character that the crew apparenly all knew VERY well, but we the audience had NEVER seen before.
The creatively bankrupt writers on Enterprise obviously thought it worth while to create a characters known only as "chef" who not only was never shown on screen, but they did not even bother to give a name.
I'm just wondering why they abandoned the entire notion of secondary characters especially on shows where such characters might have improved the dramatic situations?