In a way Voyager wrote itself into a corner where it couldn't develop any characters. TNG and DS9 characters got most of their development externally. The farengi with Zek and Moogie, Kira with the prophets and various Bajorans, Data with Lore and Soong, Worf with other Klingons. In Voyager even having the Kazons as recurring characters was a little absurd, there's no way they should have been able to keep up with Voyager's speed over two thousand light years. They brought each character to the logical finishing point of their initial arcs in the second season. They had two choices: Bring in a new character with an inexhaustible arc, or break the premise to allow recurring characters from outside the ship.