It was all lazy, the Borg and Cybermen wouldn't even make an alliance, they are not the same thing.
The Cybermen are individuals who strip away emotion, the Borg on the other hand merge minds into a collective conscience. One side cuts while the other blends yet both become almost the same thing.
I think a series of one offs might have been better showing the universes meshing.
Enterprise era: The NX01 returns to Earth to find it very different and under control of the Daleks through Robomen and Ogruns, they encounter the first Doctor.
TOS era: The Federation and Klingons go to war and bring their battle to the Eternals, here is the Fifth Doctor
TNG era: A invasion is under way by the Cybermen who have began campaigns on human colonies.
DS9 era: The Dominion poses a threat to the Alpha Quadrant, the Dominion being the founders and their shock troops the Sontarrans.
VOY era: The crew encounter the flourishing Silurians who left Earth a long time ago.
Then it could all culminate in a Timelord or Master plot to allow Gallifrey to win the Time War and avoid the Moment.