Are we sure the Borg only sent one cube in First Contact?
I mean, there's only the one cube by the time Picard arrives, but the battle had been going on for a while.
I think the Borg are aware of just how dangerous the Federation is.
Worst-case-scenario, the force you sent wins and assimilates the Federation and transforms into something you'll have to destroy.
So the Borg are reluctant to commit a truly huge force because then they might need to send an even larger force to wipe out the first force.
I mean, there's only the one cube by the time Picard arrives, but the battle had been going on for a while.
I think the Borg are aware of just how dangerous the Federation is.
Worst-case-scenario, the force you sent wins and assimilates the Federation and transforms into something you'll have to destroy.
So the Borg are reluctant to commit a truly huge force because then they might need to send an even larger force to wipe out the first force.