^I fixed the link. Thanks.
The problem with the Borg was that, as originally conceived, they were just an impersonal force of nature, and since story is fundamentally driven by character, you can't tell many stories about something impersonal. So it was an intrinsically flawed concept from the beginning, at least from a dramatic perspective. The only way they could do more than one story about the Borg was by changing the concept to personalize them more.