This really makes the Borg less frightening as enemies. Genocidal maniacs on a rampage are dull;
And yet the Federation has never actually faced a genocidal power capable of annihilating all life within the Federation before. And I dare say that the Borg in Star Trek: Destiny
are much more frightening, and make for much better villains, than they have in any Star Trek
story since "Scorpion" or Star Trek: First Contact
. The Federation has really never faced its own imminent genocide before.
Why would something as old as the Borg change merely because it met a bald human and then a redheaded one?
The destruction of the transwarp conduit network in "Endgame." It rendered the Collective unable to use transwarp drive and represented the greatest setback they've had from any species apart from 8472. As such, they came to view the Federation as an existential threat requiring immediate extermination.