USS Triumphant wrote:
They were more threatening as a faceless force of nature.
I agree. But they're also harder to tell stories about that way. Stories are about people, after all, so a totally depersonalized threat isn't very conducive to drama. That's why TNG retconned the Borg from being totally uninterested in living beings in "Q Who" (remember, the drones there were incubated from embryos) to suddenly giving a damn about humanoid authority structures and assimilating Captain Picard in "The Best of Both Worlds." It was necessary to give them a voice and a more personal focus in order to tell more stories about them. And thus we also got Hugh and Seven of Nine and the Borg Queen.
It's not the first time or the last that an impersonal alien menace in SFTV was given a more personalized individual who could function as a character rather than an unfocused threat. Doctor Who
did it when they introduced Davros, the creator of the Daleks. Dalek stories had grown rather stale and repetitive by that point -- Terry Nation was basically plagiarizing his own earlier stories without realizing it -- and once this was pointed out to him, he worked with the producers to add something fresh to the concept, and thus Davros was born in "Genesis of the Daleks," and was featured in every subsequent Dalek story until the end of the original series. And later, Stargate SG-1
had the Replicators, which were just insectlike self-replicating robots for several seasons but then "evolved" into androids so they could talk and have personalities and participate in stories as characters. Eventually you run out of stories to tell about taking on a faceless threat, because there are only so many ways to tell it. Giving it a face and a voice allows writers to use more of the tools in their kits.